3) chapter 1 - defining & measuring malnutr (pgs 15-32)

7/30/2019 3) Chapter 1 - Defining & Measuring Malnutr (Pgs 15-32)

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Malnutrition literally means bad nutrition

and technically includes both over- andunder- nutrition. In the context of develo-ping countries, under-nutrition is generallythe main issue of concern, though indu-strialization and changes in eating habitshave increased the prevalence of over-nutri-tion. Nonetheless, within the context ofWorld Food Programme (WFP) programsand assessments, malnutrition refers tounder-nutrition unless otherwise specified.

WFP defines malnutrition as a state inwhich the physical function of an indi-vidual is impaired to the point wherehe or she can no longer maintain ade-quate bodily performance process suchas growth, pregnancy, lactation, physi-cal work and resisting and recoveringfrom disease.

Malnutrition can result from a lack ofmacronutrients (carbohydrates, pro-tein and fat), micronutrients (vitaminsand minerals), or both. Macronutrient

deficiencies occur when the body

adapts to a reduction in macronutrientintake by a corresponding decrease inactivity and an increased use of reser-ves of energy (muscle and fat), ordecreased growth. Consequently, mal-nourished individuals can beshorter(reduced growth over a prolon-ged period of time) and/or thinnerthan their well-nourished counter-parts. 'Hidden Hunger', or micronu-

trient malnutrition, is widespread indeveloping countries. It occurs whenessential vitamins and/or minerals arenot present in adequate amounts in thediet. The most common micronutrientdeficiencies are iron (anaemia), vita-min A (xerophthalmia, blindness), andiodine (goiter and cretinism). Others,such as vitamin C (scurvy), niacin

(pellagra), and thiamin or vitamin B1(beriberi), also can occur during acuteor prolonged emergencies when popu-lations are dependent on a limited,unvaried food source.

MEASURING AND INTERPRETING MALNUTRITION AND MORTALITY 15

Defining and Measuring

Malnutrition

1CHAPTER

Measurement of malnutrition in children and adults

Anthropometric indices

What they are

How to calculate Z-scores and percentage of median

How to calculate body mass index (BMI)

Micronutrient deficiencies: definitions, clinical and biochemical assessments, and

commodity testing

Iron

Vitamin A

Iodine


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MEASURING MALNUTRITIONAnthropometric1 information can be usedto determine an individual's nutritional

status compared with a reference mean. Italso can be used to determine the preva-lence of malnutrition in a surveyed popu-lation. Acute and chronic malnutrition ismeasured and quantified through anthro-pometric tools. Within both emergencyand development contexts, population-based nutrition indicators can be a usefultool for assessment, prioritization and tar-geting. The basic information and measu-rements that constitute anthropometricmeasurements in children are:

These measurements are the key buildingblocks of anthropometrics and are essen-tial for measuring and classifying nutritio-nal status in children under 5 years. More

detailed information on anthropometricmeasurement techniques and recommen-ded equipment can be found in Annex 2.

Measurement of malnutritionin children under 5 yearsPhysical growth of children (under 5 years)is an accepted indicator of the nutritionalwell-being of the population they repre-sent. Adults and older children can access

proportionally larger reserves of energythan young children during periods ofreduced macronutrient intake. Therefore,the youngest individuals are most at riskfor malnutrition. For assessment of acutemalnutrition, children are more vulnerableto adverse environments and respond rapi-

dly to dietary changes, they are also moreat risk of becoming ill, which will result inweight loss. Consequently, their nutritional

status is considered a good gauge for popu-lation-based malnutrition. For assessmentof chronic malnutrition, children during thedevelopmental years are susceptible to ske-letal growth failure in ways that adults arenot and are a good reflection of long-termnutritional issues. Therefore, the surveyresults of the under-5-years population areused to draw conclusions about the situa-tion of the whole population, not just ofthat age group.

Reference populationTo determine a child's nutritional status,you need to compare that child's statuswith a reference for healthy children.References are used to compare a child'smeasurement(s) with the median for chil-dren of the same sex and age for height-

for-age and weight-for-age, or to childrenof the same sex and height for weight-for-height. The internationally accepted refe-rence was developed by the CDC and itsNational Center for Health Statistics(NCHS) using data collected from a popu-lation of healthy children2.The World Health Organization (WHO)adopted the NCHS reference curves forinternational use. Evidence has shown

that the growth patterns of well-fed, heal-thy preschool children from diverse ethnicbackgrounds are similar and consequentlyare applicable for children from all racesand ethnicities. These references are usedby agencies involved with nutritionalassessments and analysis, including WFP.

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1 Anthropometry is the measurement of the proportions of the human body.

2 The NCHS reference was established in 1977 using two different child populations: 0-36 months, lying recumbent,

and 2-18 years, measured standing. Length measurement is always greater than height measurement for children.

When interpreting data for children around 24 months it should be noted that wasting and stunting rates may peak

as a result of the overlapping data sets.

Age Sex Length Height Weight Oedema


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MEASURING AND INTERPRETING MALNUTRITION AND MORTALITY

DEFINING AND MEASURING MALNUTRITION

17

1CHAPTEREXPRESSIONS OF NUTRITION INDICES

Anthropometric indices can be expressedin relationship to the reference popula-

tion in two different statistical terms:standard deviations from the median orpercentage of the median.

1.1 Standard deviations, or Z-scoresThis is the preferred expression foranthropometric indicators in surveys. It isthe difference between the value for anindividual and the median value of thereference population for the same age or

height, divided by the standard deviationof the reference population. In other

words, by using the Z-score, you will beable to describe how far a child's weightis from the median weight of a child at

the same height in the reference value.

1.2 Percentage of medianThe percentage of median is common-ly used and recommended for admis-sion/discharge criteria for selectivefeeding programs.

Percentage of median is the ratio of thechild's weight to the median weight of a

child of the same height in the referencedata, expressed as a percentage.

Z-SCORE =measured value - median of reference population

standard deviation of the reference population

Example 1.1 Calculation of Z-score for weight-for-length

A little boy measures 84 cm in length and weighs 9.9 kg.

By referring to the reference population data in Annex 3.1, you find that the referen-

ce median weight for boys of 84 cm is 11.7 kg and that the standard deviation for the

reference distribution for boys of 84 cm is 0.908. Using these values, and the formu-la provided, you can calculate a weight-for-length Z-score for this child.

Weight-for-length Z-score = 9.9 kg - 11.7 kg

0.908

= -1.98 Z-scores

Therefore, this child is 1.98 standard deviations (or Z-scores) below the mean

weight-for-length. Similar calculations could be performed for height-for-age andweight-for-age.

PERCENTAGE OF THE MEDIAN = x 100measured weight of the child

median weight of the reference population


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18

1.3 Oedema as a confounding factorOedema as a confounding factor: Childrenwith edema should always be classified as

having severe acute malnutrition regardlessof their weight-for-height or weight-for-agez-score or percent of median. Theseanthropometric indices can be calculatedfor children with edema, and computer pro-grams, such as the EpiNut module of EpiInfo, will automatically calculate them forchildren with edema along with all otherchildren in the survey. Regardless, even ifthe indices are calculated and included in

the final survey dataset, the weight-for-height and weight-for-age indices should beignored when deciding which children haveacute malnutrition. Of course, edema hasno effect on height-for-age indices.Oedema increases weight due to the accu-

mulation of fluids; therefore, indices such asweight-for-height and weight-for age will notbe representative of the true anthropometric

status. Z-score should not be calculated forthese children, as the weight measurementwill not be valid. When oedema is present inboth feet (bilateral pitting oedema) a child isconsidered severely malnourished, regar-dless of his weight-for-height Z-score

Example 1.2 Calculation of percentage of the median weight-for-length

A little boy is 84 cm tall and his weight is 9.9 kg. Using the weight-for-height table inAnnex 3.2, you can see that the median height for a boy measuring 84 cm is 11.5 kg.

Using the percent median formula given, you can calculate the weight-for-height

percentage of the median for this boy:

Percentage of the median weight-for-length = 9.9 kg x 100

11.5kg

= 86.1% of the median weight-for-length

Therefore, this child is 86.1% of the median weight-for-length. A similar approach

can be used for height-for-age and weight-for-age.

3 Nutritional oedema is always bilateral. If the accumulation of fluid is only in one foot, it might be the symptom

of another medical condition that will require further investigation from the medical team.

Oedemous pitting occurring as a result of malnutrition


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19

1CHAPTER

Reporting of survey results in Z-score or percentage of the median?

The preferred method of expressing prevalence of malnutrition obtained through sur-vey results is in Z-scores, primarily because the percentage of the median does not

take into account the standard deviation associated with the reference distribution of

weight for each height category. As the child grows, the standard deviation associa-

ted with the reference median increases more slowly than the median weight. The

weight of a child who is 100 cm tall is further from the reference distribution than that

of the child who is 80 cm tall, and his weight deficiency, compared with the reference

standard deviation, is greater than that of the child of 80 cm.

The Z-score expression takes into account the standard deviation of the distributionand thus standardizes weight deficiencies, regardless of the height of the child. Use of

the median height-for-age and weight-for-age is also calculated without taking into

account the distribution around the median in the reference population.

Moreover, the Z-score is a more statistically valid comparison to the reference popu-

lation than the percentage of the median. When using Z-scores, all malnourished chil-

dren, regardless of age and/or height, are likely to be actually classified as malnouri-

shed. Since the percentage of the median only uses two factors to calculate malnu-

trition, as opposed to the three factors used in Z-score calculations, percentage of the

median has less likelihood of capturing all the malnourished children. Therefore, when

Z-scores are used to define malnutrition, the number of children classified as malnou-

rished is higher than if the percentage of the median is used, and it is a more statisti-

cally uniform approach to defining malnutrition.

Percentage of the median is primarily used as a programmatic tool for selective fee-

ding programs (because of ease of calculation and understanding); therefore, program

reports will often express malnutrition in percentage of the median. Bearing these

points in mind, WFP recommends that anthropometric survey results are expressed

foremost in Z-scores. If circumstances call for, results can be presented secondarilyin percentage of the median along with Z-scores.


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EXPRESSION OF NUTRITION INDICATORSTo define nutritional status based onanthropometric indices, cutoff values are

used. Nutrition indicators are a tool tomeasure and quantify the severity of mal-nutrition and provide a summary of thenutritional status of all children in themeasured group. It provides a method bywhich the nutritional status of a group canbe compared easily over time or with othergroups of interest.

Prevalence of malnutrition in childrenOnce the comparisons are made betweenindividual nutritional status and the referen-

ce population, you can calculate the preva-lence of malnutrition among the populationthe individuals represent. The prevalence ofmalnutrition is equal to the number of mal-nourished children divided by all childrenassessed in the population. To help you inyour calculations, you can use statisticalsoftware, such as Epi Info or the newlydeveloped Nutrisurvey, which will automa-tically calculate the nutritional indices.

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Table 1.1 Classification of malnutrition for weight-for-height, height-for-age,and weight-for-age based on Z-scores

Classification

Adequate

Moderately malnourished

Severely malnourished

Z-score values

-2 < Z-score < + 2

-3 < Z-score < - 2

Z-score < - 3

Table 1.2 Classification of malnutrition for weight-for-height, height-for-age,and weight-for-age based on percentage of the median

Classification

Adequate

Mildly malnourished

Moderately malnourished

Severely malnourished

Weight-for-height (%)

90-120

80-89

70-79


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21

1CHAPTERDetermining the prevalence of acute malnu-trition in a population can be useful inmany different ways. Malnutrition prevalen-

ces are used to define emergency levels, tojustify initiation or suspension of nutritionprograms and to verify needs assessment.However, the decision to implement nutri-tion programs should be based on thoroughanalysis of factors such as the environment,food security and public health issues. Evenif the overall food needs of a population aremet, there may be inequities in the distribu-tion system, disease outbreaks and other

social factors that can cause an increase inthe prevalence of malnutrition among cer-tain vulnerable groups.

Measuring malnutrition among adultsThe anthropometric indices used with chil-dren (weight-for-height, height-for-age andweight-for-age) cannot be applied to adults.There is no internationally accepted anthro-

pometry reference for adults, and the prin-ciples of a standardized growth curve arenot applicable to adults. Consequently, analternative measure is used for adults.

Body Mass Index (BMI)The most useful measure of malnutritionin adults is the body mass index (BMI)4.

BMI is calculated by dividing the weight(in kilograms) by the height (in meterssquared). Pregnant women or adults withoedema are excluded from surveys toassess BMI because of the bias introdu-ced by weight gain not related to nutritio-nal status. BMI is calculated as:

An example of a BMI calculation is providedin Example 1.4. The BMI cutoff values areapplied equally to both sexes (Table 1.3)and the same cutoffs are applicable to alladults except pregnant women and indivi-

duals with oedema. BMI is not used forpregnant women due to the weight gainassociated with the pregnancy.

Example 1.4 Calculation of BMIA young, non-pregnant woman's height is 1.60 m and her weight is 50 kg.

Using these values in the BMI formula, you would calculate her BMI as follows:

BMI = 50kg

1.6m2

= 19.5Therefore, the woman's BMI is 19.5

4 Some populations, such as the Kenyan Samburu and the Sudanese Dinke, are genetically very tall and should

not be assessed using BMI cutoffs.

Table 1.3 Classification of adult malnutrition (also called Chronic Energy Deficiency)using Body Mass Index (BMI)

Malnutrition classification

Mild

Moderate

Severe

Cutoff point using BMI

17 BMI


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22

Low birth weight as ameasurement of mother and infant

nutritional status

Small babies - especially low-birth-weight (LBW) babies - are effectivelyborn malnourished and are at higher riskof dying in early life. LBW is defined as abirth weight of less than 2,500 g. Thisindicator is widely used because itreflects not only the status (and likelynutritional health risks) of the newborn,but also the nutritional well-being of themother. That is, while a low birth weightresults from many other factors (includ-ing smoking, alcohol consumption dur-ing pregnancy, genetic background andother environmental factors), it remains agood marker for a mother's weight gainand the fetus' development during preg-nancy. The growth and development ofbabies are affected by their mother's pastnutritional history. Malnutrition is an

intergenerational phenomenon.

A low-birth-weight infant is more likelyto be stunted (low height-for-age) by theage of 5 years. Such a child, without ade-quate food, health and care, will becomea stunted adolescent and later, a stuntedadult. Stunted women are more likely togive birth to low-birth-weight babies, per-petuating the cycle of malnutrition from

generation to generation. In addition, thelow-birth-weight infant remains at muchhigher risk of dying than the infant withnormal weight at birth. The proportion oflow-birth-weight infants in a populationis the major determinant of the magni-tude of the mortality rates and a proxyindicator for maternal malnutrition.

Low birth weight as an indicator is usuallycollected through monitoring data such asbirth records and clinic registrations. Assuch, there is usually uncertainty and biasassociated with such records because it is

a self-selective sample. In some instances,where reliable birth weight data is avail-able at the household level, birth weight

can be collected through a survey. Moreinformation on equipment used to meas-ure birth weight and infant weight can befound in Annex 2.

MICRONUTRIENT DEFICIENCIESMicronutrient deficiencies represent aless visible, but often devastating, formof malnutrition that can be particularlyprevalent among WFP's beneficiarypopulations already lacking sufficientquantity and/or quality of food. Thereis a close relationship between malnu-trition, which is often linked to lack offood, and specific micronutrient defi-ciency diseases that are associatedwith consumption of foods poor inmicronutrients. Since WFP's benefici-aries frequently have limited access to

a varied diet, a large proportion ofthem are also likely to suffer multiplemicronutrient deficiencies. WHOprevalence data for micronutrient prob-lems suggest that 4 million women andyoung children are vitamin-A deficient,almost 7 million school children areiodine-deficient and 7 million womenof childbearing age are anaemic.Deficiences of one or more of these

micronutrients usually means there arealso deficiencies of other micronutri-ents, because the origin of these defi-ciencies, a deficient diet, means thatother micronutrients are also presentin insufficient amounts.

Currently, most international effortsare directed toward reducing the

prevalence of deficiencies of iron, vita-min A, iodine, zinc and folic acid.According to WHO, deficiencies iniron, vitamin A and zinc each rankamong the top 10 leading causes of


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death in developing countries. Mostpeople affected by micronutrient defi-ciencies do not show overt clinical

symptoms, nor are they necessarilyaware of the deficiency. Micronutrientdeficiencies represent a particularthreat to the health of children under5 years and pregnant women.

The following section will focus on thethree most common micronutrient defi-ciencies (iron, vitamin A and iodine).Known effects of these micronutrientdeficiencies include impaired physicaland mental growth among children, iron-deficiency anaemia, maternal mortality,low adult labor productivity and blind-ness. Although micronutrients arerequired in tiny amounts, the conse-quences of severe deficiencies can becrippling or fatal. However, deficienciesin other micronutrients can occur in a

population where the food supply is inad-equate or not diversified. Severe niacindeficiency causes pellagra, a diseaseaffecting the skin, gastrointestinal tractand the nervous system. Pellagra is oftencalled the 4 Ds: dermatitis, diarrhea,dementia and death. Severe thiaminedeficiency can cause beriberi, whilesevere vitamin C deficiency will causescurvy. Scurvy is recognized by painful

joints, swollen and bleeding gums, andslow healing or re-opening of wounds.

Recently zinc deficiency has been gar-nering more attention. Although severezinc deficiency is rare, mild-to-moderatezinc deficiency is quite commonthroughout the world. It is estimatedthat some form of zinc deficiency affectsabout one-third of the world's popula-tion, with estimates ranging from 4% to73% across subregions. Worldwide,zinc deficiency is responsible for approx-imately 16% of lower respiratory tract

infections, 18% of malaria and 10% ofdiarrhoeal disease. In total, 1.4% ofdeaths worldwide (2002) were attributa-

ble to zinc deficiency. Serum and plasmazinc concentrations are the most widelyused biochemical markers of zinc status .Circulating zinc concentrations is a usefulindex in assessing zinc status at the pop-ulation level. The collection and prepara-tion of intravenous blood samples forzinc analysis should be performed in acontrolled environment to ensure accu-rate assessment. Contaminant sources ofzinc can also be introduced by the techni-cian handling the blood, through sweat,fingernails or saliva (via sneezing orcoughing), zinc being present on theequipment used (needles, tubes, etc), andtransportation of dust particles; therefore,it requires an extremely controlled envi-ronment and special equipment to ensurethat the results are accurate. In most set-

tings be introduced by the technicianhandling the blood, through sweat, fin-gernails or saliva (via sneezing or cough-ing), and transportation of dust particles;therefore, it requires an extremely con-trolled environment to ensure that theresults are accurate. In most settings inwhich WFP would be involved in a nutri-tion survey these conditions would bevery hard to achieve. Expert advice

should be sought before attempting toassess zinc status of the population.

To assess some micronutrient deficien-cies, blood or urine needs to be collect-ed. Trained phlebotomists or lab techni-cians should be hired to collect bloodsamples when necessary. Where onlyfingerprick samples are needed, surveystaff can be trained. Because of the inva-siveness of such procedures, care mustbe taken to assure and respect therights of individuals by followingeach country's guidelines in this area.



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1CHAPTER


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It may be necessary in some regions toobtain written consent from parents toallow their children to participate in the

survey. In addition, even given parentalapproval, consent from the child is nec-essary. Confidentiality of results alsoneeds to be considered. Feedback to theindividuals, families and communitiesregarding significant health problemsshould also be considered. For moreinformation about ethical issues, pleaserefer to Chapter 5.

If blood is going to be collected, alwaysfollow these universal precautions foryour own safety and the safety of theothers. These steps will prevent thetransmission of diseases such as hepati-tis B, HIV and other infections carriedin the blood.

1. Always explain the procedure to the

individual (child and adult). Somemicronutrient deficiency testing ismore invasive than measuringweight and height. The sight ofblood or a needle prick might fright-en some individuals. Use reassuringterms and be empathic.

2. Always obtain informed consent. Ifthey do not agree, do not take asample.

3. Always be careful around biohaz-ardous materials. Never allow achild or any individual to play witha piece of equipment.

4. Always wear sterile latex gloves.5. Only use one needle or lancet per

person.6. After pricking the skin, place the

needle in a puncture-resistant con-tainer such as the commerciallyavailable red biohazardous contain-ers with the logo for biohazardouscontent. Do not leave it on the tableor the floor.

7. Always dispose of all biohazardousmaterial properly. The biohazardouscontainers should be disposed at the

local health facility that uses standardprocedures for biohazardous contents.

Iron deficiencyBecause anaemia is the most commonindicator used to screen for iron deficien-cy, the terms anaemia, iron deficiency,and iron deficiency anaemia are oftenused interchangeably. There are differ-ences between these conditions whichare explained later. Prior to the develop-

ment of iron deficiency anaemia, thereare mild-to-moderate forms of iron defi-ciency, in which various cellular func-tions are impaired.

Iron deficiency

According to WHO, iron deficiency is themost common nutritional disorder in theworld . It affects at least half of all preg-nant women and young children in

developing countries. Iron deficiencyoften results from a lack of bioavailableiron in the diet, but also can occur dur-ing a period of rapid growth (pregnancyand infancy), when the body needs moreiron. Another common cause is increasedblood loss, such as gastrointestinalbleeding due to hookworm or urinaryblood loss due to schistosomiasis.

Anaemia

Anaemia is defined by low hemoglobinlevels and can be caused by nutritionaldeficiencies of iron, vitamin B12, vitamin

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WFP recommended tests for micronutrientdeficiencies Anemia: Hemoglobin

Vitamin A Deficiency: Night Blindness

and/or Serum Retinol

Iodine Deficiency: Urinary Iodine


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A and folic acid. It also can result fromchronic infections (malaria, worm infesta-tion, etc.), severe blood loss or inherited

abnormalities such as thalassaemia.Multiple causes of anaemia can coexist inan individual or populations and con-tribute to its severity; however, the mostcommon cause of anaemia is iron deficien-cy. Children younger than 24 months areespecially at risk for anaemia, which slowstheir mental and psycomotor develop-ment, only part of which may be reversiblelater in life. In older children, the ability toconcentrate and perform well in school ishindered. Among adults, anaemia is a seri-ous risk to mothers in childbirth: everyday some 140 women die in childbirthbecause of severe anaemia.

Iron deficiency anaemia

A sufficiently large lack of iron can causeanaemia. Although some functional con-

sequences may be observed in individu-als who have iron deficiency withoutanaemia, cognitive impairment,decreased physical capacity and reducedimmunity are commonly associated withiron deficiency anaemia. In severe irondeficiency anaemia, capacity to maintainbody temperature may also be reduced.Severe anaemia is also life threatening.

Because anaemia can contribute to mater-nal mortality, infant morbidity, infant mor-tality, intrauterine growth retardation andlow birth weight, WHO recommendsscreening of all pregnant women foranaemia.

Clinical signs and biochemical test

for anaemia

Using clinical pallor of the nails or eyes(inferior conjunctiva) to diagnose anaemiaon a population basis should be avoidedbecause these clinical signs are very sub-jective and not precise. A more reliable

and easy method is to test the hemoglobinconcentration in the blood. Specific equip-ment is needed for the testingo.

latex gloves for you and your assistant alcohol pads sterile, dry gauze pads disposable needles (lancets such

as Tenderlett) microphotometer (such as the

HemoCue) microcuvettes for the photometer adhesive bandages

Hemoglobin testing using

the HemoCue method

In the field, hemoglobin levels are deter-mined by using a photometer, such asthat manufactured by HemoCue. Thiscompany also offers essential training forthe proper use and care of the testingequipment. A video is also available onHemoCue's Web site at URL:

http://www.hemocue.com/hemocueus/sida_3.asp.The basic procedure is as follows:

1. Ensure ethical clearance from the

host government and obtain personalconsent from each individual.

2. Have the analyser turned on and thecuvette holder in the outer position;the screen should say READY.

3. Take a microcuvette out of the vialand reseal the vial.

4. After cleaning the finger of the childor adult with alcohol pads, hold thefinger firmly and prick with a dispos-able lancet (small disposable needle).

5. After the puncture has been made,apply gentle pressure as needed toextrude a large drop of blood.



25

1CHAPTER

Portable HemoCue machine


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6. Release the pressure on the finger andwipe off the drop with a dry, lint-free wipe.

7. Wipe away an additional one or two

large drops, alternately applyingand releasing pressure on the fingeras needed.

8. Apply the microcuvette of the HemoCueto a drop of blood from the same finger-prick. Blood is drawn into the cuvetteby capillary action. Hold the cuvette inplace until the entire teardrop-shapedcavity is filled with blood.

9. After wiping off any excess bloodfrom the sides of the cuvette, place itin the cuvette holder and insert it intothe HemoCue.

10. Read the hemoglobin concentration[Hb] and record the hemoglobin con-centration to one decimal point.

11. Apply an adhesive bandage on the fin-ger of the individual.

Errors that can occur due to incorrecthandling of microcuvette are: microcuvette not completely filled; contamination of the optical eye with-

in the hemoglobin instrument; introduction of air bubbles (i.e., when

filled from the edge instead of the tip); and

cuvette exposed to heat and humiditybecause of incorrect storage (i.e., whenthe lid is not closed properly). Note

that once the container has beenopened they may not stay active untilthe indicated expiry date.

Other methods, such as WHO's hemoglo-bin color scale and the Sahli method, havebeen used to determine hemoglobin con-centration; however, these methods areboth highly subjective and therefore lessaccurate than the more objectiveHemoCue method.are not recommendedby WFP. Compared to the HemoCuemethod, an objective method, the hemo-globin color scale and the Sahli methodhave low accuracy. They are not recom-mended by WFP. A program officer pre-sented with a report containing hemoglo-bin concentrations measured with thehemoglobin color scale or the Sahlimethod should be aware that such meth-

ods lack precision.

Use of hemoglobin concentration

to determine status

International cutoffs have been created toclassify the status of individuals based onthe amount of hemoglobin in the blood.

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Table 1.4 Hemoglobin cutoffs to define anaemia in individuals living at an

altitude 15.0 years

Men > 15.0 years

Hemoglobin cutoff (g/dL)

11.0

11.5

12.0

12.0

13.0

UNICEF/UNU/WHO (2001) and INACG (2002)


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Adjustments should be made on thebasis of pregnancy status, altitude andfrequency of cigarette smoking. The

concentration of hemoglobin in bloodnormally increases as children get older.During adolescence, hemoglobin pro-duction increases even more as a resultof accelerated growth. For these rea-sons, age-specific values must be usedto define anaemia in children. Also,men have higher hemoglobin concentra-tions than women.

In women with adequate iron nutrition,hemoglobin concentration starts to fallduring the early part of the first trimester,

reaches its lowest point near the end ofthe second trimester and then graduallyrises during the third trimester; trimester-specific adjustments hence have beendeveloped. At elevations above 1000 m,hemoglobin concentrations increase as anadaptive response to the lower partialpressure of oxygen and reduced oxygensaturation of blood.



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1CHAPTER

Table 1.5 Adjustments to hemoglobin cutoffs for pregnancy, altitude andcigarette smoking (INACG 2002)

Stage of pregnancy (trimester)

First

Second

Third

Trimester unknown

Altitude (m) range

m < 1000

1000< m


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Vitamin-A Deficiency (VAD)

Vitamin A is a fat-soluble vitamin requiredfor normal growth and development. It is

involved in the functioning of the eyes aswell as the immune and reproductive sys-tems, while also helping to keep skinhealthy. For children, lack of vitamin A maycause severe visual impairment and blind-ness. Note that clinical signs (nightblind-ness and other xeropthalmia) present thetip of the iceberg of VAD. Many more chil-dren, not suffering from clinical signs ofVAD, have low circulating levels of vitaminA (biochemical indicator of VAD) andhence suffer consequences of higher risk ofmorbidity and mortality. VAD significantlyincreases the risk of severe illness, and evendeath, from such common childhood infec-tions as diarrheal disease and measles. Notonly is VAD is the leading cause of child-hood blindness across developing coun-tries, it also affects children's immune sys-

tems and is directly responsible for around10.8 million deaths each year. Eliminatingvitamin A deficiency would cut child deathsdue to measles alone by 50 percent.

Women and vitamin-A deficiency

Women, whether pregnant or not, shouldbe asked about nightblindness during theirprevious pregnancy in the last 3 years, andthat should have been a pregnancy carried

to full term. However, pregnant women areparticularly vulnerable to VAD, particularlyduring the last trimester of pregnancy

when demand by both the fetus and themother is highest. Among pregnantwomen in high-risk areas (where food con-taining vitamin A is rare), the prevalence ofnight blindness often increases during thelast trimester. Night blindness during preg-nancy is highly associated with malnutri-tion, anaemia and increased morbidity inwomen and their infants. To assess theprevalence of night blindness among preg-nant women, you ask them about theirnight blindness history for their most pre-vious pregnancy.

Clinical assessment of VAD:

night blindness

Night blindness is the inability to see afterdusk or at night and is the most commonvision problem resulting from severe vita-

min-A deficiency. In many regions, a localterm is used to define night blindness. Toassess night blindness, ask the individual ifhe or she has any problem seeing in thedark, at night or in a darkened room com-pared to their eyesight during the day or in alighted room. For children, you may need toobtain the information from the child'smother or caregiver. Whenever possible, usethe local term for night blindness.

28

Table 1.5 Cutoffs for vitamin A deficiency (VAD) using retinol concentration

Serum retinol

(micrograms/dL)

< 10

10 - 19.9

20 or above

Serum retinol

(micromols/L)

< 0.35

0.35 - 0.69

0.7 or above

WHO definition of

deficiency*

Severe

Moderate

None

IVACG definition

of deficiency**

Deficient

None

* WHO. Indicators of vitamin A deficiency and their application in monitoring and evaluating intervention

program. WHO/NUT/96.10. World Health Organization, 1996. Geneva, Switzerland.

** Sommer A, Davidson FR. Assessment of vitamin A deficiency: the Annecy Accords. Journal of Nutrition

2002;132:2845S-2850S.


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WHO has created a scheme for

classifying night blindness by

interview, using four questions:

1. Does your child have any problem see-ing in the daytime?

2. Does your child have any problem see-ing at nighttime?

3. If (2) is yes, is this problem differentfrom other children in your communi-ty? (this question is particularly appro-priate where VAD is not very prevalent)

4. Does your child have night blindness(use the local term that describes thesymptom)?

Biochemical assessment of VAD:

serum retinol concentrations

At the individual level, retinol does notreflect liver stores of vitamin A and may beaffected by other factors, such as infectionand protein-energy malnutrition. However,it does allow for the detection of subclini-

cal vitamin-A deficiency at a level that doesnot lead to vision problems, but does lowerimmune response and hence increases therisk of morbidity and mortality.

At the population level, you measure theserum or plasma retinol concentration todetermine vitamin A status. The proportionof individuals with low retinol levels reflectsthe prevalence of VAD in children and adults.

The prevalence in pregnant women may bea bit higher than the overall adult prevalence.

For assessment of vitamin A status, thehigh-performance liquid chromatography(HPLC) method currently is used, but it isexpensive and time-consuming. Thismethod requires the handling and trans-portation of blood specimens, with skilledtechnicians needed to operate the equip-ment. Further, it requires freezing of sam-ples, and transportation can be difficult.

A surrogate for plasma retinol is plasmaretinol-binding protein (RBP). It can be

measured by radical immunodiffusion, atechnique that is much simpler and lessexpensive than HPLC. RBP can also be

measured in a rapid field test using driedblood spots. One alternative is to measureretinol levels by using filter paper bloodspot samples. Retinol can be measured ina small sample of serum obtained from afinger pricked by sterile lancet.

At this time there is no field-based methodfor testing for Vitamin A content in oil.

Iodine Deficiency Disorders (IDD)

Iodine is a mineral that is part of the hor-mones produced by the thyroid glandlocated in the front of the neck. Wheniodine intake falls below recommendedlevels, the thyroid may no longer be able tosynthesize sufficient amounts of thyroidhormone. The resulting low level of thyroidhormones in the blood is responsible for

the damage done to the developing brainand the other harmful effects known col-lectively as the iodine deficiency disorders.

Iodine deficiency can cause a goiter - aswelling of the thyroid gland in the neck.Iodine deficiency is also associated withsevere mental disabilities due to perma-nent brain damage in the fetus and infantand retarded psychomotor development

in the child. Such disorders can be pre-vented by iodising all edible salt.

Clinical signs of IDD: goiter

Palpation of the thyroid is performed as anindicator of iodine deficiency. However, thistechnique is less reliable when there are fewgoiters and/or when the goiters are relativelysmall. The thyroid size is slow to respond tochanges in iodine nutrition. Therefore assess-

ment of thyroid size through palpation maynot be representative of the current iodinenutrition status. Consequently, palpation isnot preferred by WFP; nonetheless, it often isstill used in the absence of other tests.



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Biochemical assessment

of IDD: urinary iodine

The measurement of the iodine concen-

tration in urine is the recommended wayto assess the current iodine status of apopulation5. Urinary iodine (UI) concen-tration is a good indicator of iodineintake because most of the ingestediodine is excreted in the urine.

At the individual level, iodine excretionvaries throughout the day due to hydra-tion and iodine intake. At the population

level, the median UI concentration ofcasual specimens will be representativeof the population's recent iodine intake.For assessing the iodine status of a pop-ulation, urine specimens from individu-

als do not need to be collected over a 24-hour period. The goal is to have a medi-an urinary iodine concentration

between 100-300 g/L(WHO/UNICEF/International Councilfor Control of Iodine DeficiencyDisorders [ICCIDD]). The urinary iodinesurvey should be used to help determinethe level of iodine needed in the salt toachieve median urinary iodine valuesbetween 100-300 g/L.

Blood samples or blood filter paper

specimens for assessing thyroid func-tion (such as thyroid stimulating hor-mone [TSH], thyroglobulin, or T4) inchildren or adults are not recommendedfor survey settings.

30

Table 1.6 Epidemiologic criteria for assessing iodine nutrition based onmedian urinary iodine concentrations in school-age children

Median urinary

iodine (g/L)

< 20

20-49

50-99

100-199

200-299

>300

Iodine intake

Insufficient

Insufficient

Insufficient

Adequate

More than adequate

iodine intake

Excessive iodine intake

Iodine nutrition

Severe iodine deficiency

Moderate iodine deficiency

Mild iodine deficiency

Optimal

Risk of iodine-induced hyperthyroi-

dism within 5 or 10 years following

introduction of iodised salt in

susceptible groups

Risk of adverse health consequen-

ces (Iodine-induced hyperthyroi-

dism, autoimmune thyroid disease)

5 The current recommendations by WHO/UNICEF/ICCIDD on urinary iodine and goiter are specific to school-age

children, those within the range of 6-12 years, although a narrower age range is acceptable, e.g., 8-10 years.

6 Testing kits are available to test for either iodite or iodate. Attention should be paid to this detail when

determining which one to order and use in the field.

Source: WHO/NHD/01.1, 2001


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Materials and procedures

for urine collection

You will need the following materials for

collecting urine samples: Disposable cups for collecting urine specimens Screw-capped tubes for urine storage

and transportation Disposable pipette for transferring urine

from cup to tube Tube labels Tube racks Cardboard with styrofoam-insert boxes Mailing/shipping labels Coolant Disposable gloves (for handling of urine

which may pose an infectious diseaserisk to handlers)

Permanent ink pens for labels Sealable plastic bags Waste disposal bags

Follow these guidelines when collectingurine samples: Always wear gloves while handling

urine specimens to reduce the risk ofinfections from the urine.

Provide each participant with a disposa-ble paper cup for urine collection.

Ask the individual to urinate directlyinto the cup. It should be filled approxi-mately halfway with urine.

Transfer approximately 3-5 mL of the urine

specimen to the screw-capped tube using adisposable pipette. (Note that urinary iodi-ne analysis generally requires 1 mL or less;however, the provision of extra urineallows for repeat analysis if necessary.)Dispose of used cups and pipettes proper-ly. The urine specimen should be labeledappropriately and placed into a tube rack.

At the end of the collection of survey informa-tion, urine specimens should be packed in batch-

es into sealed plastic bags and then into a ship-ping box or padded bag. Refrigeration during theshipping process is preferable, but not required.Various techniques are used to measure uri-nary iodine. A detailed description of the

various methods can be found in a docu-ment produced by WHO entitledAssessment of Iodine Deficiency Disorders

and Monitoring their Elimination. A guidecan also be found online at URL:http://www.who.int/nut/documents/assessment_idd_monitoring_elimination.pdf

Field methods to test for iodine in salt

Iodised salt is often a first-line defenceagainst iodine deficiencies, and there are cir-cumstances in which it is useful to test saltin order to determine coverage of iodised

salt. When iodine deficiency prevalence isestimated to be high, or when the region ofinterest is landlocked, coverage of iodisedsalt can act as a proxy indicator for iodinedeficiency. An easy-to-use field-basedmethod for testing salt has been developed.

Method:- Place a small amount of the salt to be testedon a saucer and moisten with two drops of

test reagent (a dilute acid, potassium iodideand starch solution).- If iodate (or iodite)6 is present, the saltshould immediately turn blue-purple andremain blue for several minutes before fading.Disadvantages:- If the result is not interpreted immediate-ly, colour fading may occur over time andlead to incorrect results.- These kits are specific to the form of

iodine, either potassium iodate (KIO3) orpotassium iodide (KI) salt.

Testing kits:ICCIDDc/o Centre for Community MedicineAll India Institute of Medical SciencesNew Dehli-29, IndiaEmail: [email protected]

WYD Iodine CheckerSalt Research InstituteChina National Salt Industry Corporationhttp://www.chinasalt.com.cn/SALT-3/Product1%20-%20ChinaSalt_com.htm



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32

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I World Food Programme. Food and Nutrition Handbook. Rome: World Food

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II Prudhon C. Assessment and treatment of malnutrition in emergency situations. Paris:Action Contre la Faim; 2002.

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IV Centers for Disease Control and Prevention. What is Epi Info? Atlanta: US Departmentof Health and Human Services. Available at URL: http://www.cdc.gov/epiinfo/.

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VII International Zinc Nutrition Consultative Group (IZiNCG). Assessment of the Risk ofZinc Deficiency in Populations and Options for Its Control, 2004. Available at URL:http://www.izincg.ucdavis.edu/publications/FNBv25n1supp2zinc.pdf

IX World Health Organization. Micronutrient deficiencies: battling iron deficiency anaemia.Geneva: World Health Organization; 2003. Available at URL:http://www.who.int/nut/ida.htm.

X Sanchez-Carrillo CI. Bias due to conjunctiva hue and the clinical assessment of anaemia.J Clin Epidemiol 1989;42:751-4.

XI Sharmanov A. Anaemia testing manual for population-based surveys. Calverton,Maryland: Macro International Inc.; 2000.

XII HemoCue AB. Corporate Web site. URL: http://www.hemocue.com/.

XIII International Nutritional Anaemia Consultative Group (INACG), 2002. AdjustingHemoglobin Values in Program Surveys.http://inacg.ilsi.org/file/HemoglobinValues2004.pdf

XIV Tanumihardjo SA, Blaner WS, Jiang T. MOST Technical Report. Dried blood spotretinol and retinol-binding protein concentrations using enzyme immunoassay assurrogates of serum retinol concentrations. Arlington: The MOST Project; 2002 Jun.Available at URL: http://www.mostproject.org/Assesmt%20Methods.PDF.

XV World Health Organization. Vitamin A. Available at URL:http://www.who.int/vaccines-diseases/en/vitamina/science/sci05.shtml.

XVI Sullivan KM, May S, Maberly G. Urinary iodine assessment: a manual on surveyand laboratory methods. 2nd ed. Atlanta: Emory University and UNICEF; 2000.Available at URL: http://www.sph.emory.edu/PAMM/lab/UIAssessment2.pdf.

3) chapter 1 - defining & measuring malnutr (pgs 15-32)

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