Micronutrient malnutrition III

Vanessa Velazquez-Ruiz, MD Emergency Medicine Global Health Fellow

St. Luke’s-Roosevelt Hospital

Agenda

  Iron deficiency anemia

  Overview and epidemiology

  Discuss risk factors and food sources

  Highlight the role or iron as a micronutrient and discuss some of the consequences of iron deficiency

Iron deficiency and anemia

Overview

  One of the most common nutrition disorders worldwide

  Only nutrient deficiency of significant prevalence in all develop countries

  Play a key role in oxygen and energy metabolism

  Anemia is commonly used to screen for iron deficiency

  Anemia not specific for iron deficiency

  Iron deficiency anemia represents the severe end of spectrum of iron deficiency

  Iron deficiency without anemia represent a mild form of the deficiency

Anemia

  Defined as hemoglobin concentration below -2 standard deviation of the age, sex specific reference

  Most common cutoff in hemoglobin is below

  110mg/L for children under 5 and pregnant

  120mg/L for non pregnant women

  130mg/L for men

Epidemiology

  WHO estimated 4-5 billion people with iron deficiency

  More than half preschool-aged children and women of reproductive age are anemic in many countries from South Asia and sub-Saharan Africa

  High rates in countries like Peru, Bolivia and Haiti

  Estimated 7-12% with iron deficiency in develop countries

WHO 2005

  Not all anemias are caused by iron deficiency

  In areas where the prevalence of anemia in higher than 30-40%, most is caused by iron deficiency

  Challenging in places like Sub-Saharan Africa where thalassemia and malaria are endemic.

  Vit A, Folic Acid and Vit B 12 may contribute to etiology

Risk factors

  Pregnancy

  Prematurity

  Low birth weight

  Rapid growth

  Sensitivity to cow’s milk

  Low consumption of meat

  High consumption of phytates

  Menstruation

  Nematode infection in GI

Food sources

  red meat

  Poultry

  insects

  lentils

  beans

  leafy vegetables

  pistachios

  tofu

  chickpeas

  black-eyed peas

  fortified bread, and fortified breakfast cereals

  Iron from plant sources is less easily absorbed than iron from animal sources

  Vegetarians and vegans should have a higher total daily iron intake than those who eat meat, fish or poultry

  Legumes and dark-green leafy vegetables like broccoli, are especially good sources of iron for vegetarians and vegans

Metabolism

Roles of iron in biological functions

  Hemoglobin

  Transfer of oxygen from lungs to tissue in erythrocytes

  In anemia,

Hgb content of erythrocytes is reduced -> decreasing oxygen delivery to tissue -> leading to chronic tissue hypoxia

  Myoglobin

  Found in muscle

  Transport and storages oxygen needed for muscle contraction

  10% of total body iron

  Single heme group with single globin chain

  Cytochromes

  Essential to respiration and energy metabolism

  Cyt a, b and c involved in oxydative phosphorylation and production of cellular energy

  Serves as electron carriers in transforming ADP to ATP (primary energy storage compound)

  Other iron containing enzymes

  NADH (Nicotinamide adenine dinucleotide phosphate) dehydrogenase

  Catalase

  Peroxidase

  Among other

  Iron and immune system

  Animal studies suggested some role in immune system

  No convincing evidence for humans

Pathogenesis of Iron deficiency

  Increase requirement for iron

  Negative balance between intake and loss

  Rapid growth (infancy, adolescence, pregnancy)

  Iron loss (menstrual period, transfer to fetus)

  Poor dietary intake

  For infants, iron content of milk is a major determinant

  Iron content of breast milk is low compared to cow milk, however

  50% of breast milk iron can be absorbed and only 10% of cow milk can

  After 6 months, breast feeding infants need another source of iron besides breast milk

  Abnormal iron loss

  Menstrual blood

  Occult GI blood due to sensitivity to proteins in cow milk

  Hookworm infection

  Necator americanus (greater bleeding) and Ancyclostoma duodenale

Functional consequences of iron deficiency

  Mild anemia (10-20gm/L below cutoff) : no health impairment

  Moderate anemia: reduce oxygen carrying capacity and interferes with aerobic function

  Very Severe (<50gm/L) : increase childhood and maternal mortality

Child behavior and development

  Better Birth Outcomes

  Child behavior and development

  Children with iron deficiency anemia test less well in psychomotor development

  Moderately severe iron deficiency can lead to irreversible development disadvantage

  Iron-deficiency women are at increase risk of depression

Work performance and productivity

  Reduce work performance

  Linear dose response relationship between hemoglobin concentration and performance

  Supplementation of iron in workers increases productivity

  In developing countries, a major reduction in work capacity can be of great economic consequence

  In a country where 50% of women and 20% of men are affected, the impact equals 5-7% of the national economic output.

Heavy metal absorption

  Iron deficiency children in USA have 3-4 times higher prevalence of lead poisoning

  Strong evidence of direct association between iron deficiency and increase efficiency of lead absorption

Assessment of nutritional status

  Test for iron deficiency

  One or more abnormal iron biochemical test:

  Serum ferritin

  Transferrin saturation

  Transferrin receptor

  Erythrocyte protoporphyrin

Ferritin

  Serum Ferritin is a well accepted marker of body iron

  Pros: ability to measure level form blood spots

  Contras:

  Infection and inflammation can falsely elevate levels

  Expensive for field base settings

Hemoglobin

  Field testing of anemia

  Portable photometer or standard methods

  Detection of anemia by clinical examination

  Pallor of skin, conjunctive, tongue and palms

Physical exam

Symptoms of iron deficiency

  Fatigue

  Pallor

  hair loss

  Irritability

  Weakness

  Pica

  brittle or grooved nails

  Plummer-Vinson Syndrome

  Painful atrophy of mucous membrane of the tongue, pharynx and esophagus

  Among other

Primary Health Care approaches

Iron supplementation

  1st approach

  If Prevalence of iron deficiency anemia is low (10-15%)

  Screen for anemia and supplement those found anemic

  Dosage 3mg/kg elemental iron for children under 5

  60mg elemental iron daily for adults for 3 months

  2nd approach

  Universal supplementation where the prevalence is high and where the majority are iron deficient

  Most suitable in developing countries

  UNICEF recommends a daily dose of 12.5mg of elemental iron for infants 6-12 months old

  In pregnancy WHO recommends

  6-month regimen of daily supplements containing 60mg of elemental iron +folic acid

  If the prevalence of anemia is >40%, an additional 3 month tx in postpartum periods is recommended

Limitations

  Strategy is needed to establish a system for supply and distribution of iron tablets

  Supply and distribution is not always reliable

  Poor compliance

  At higher doses (>60mg) many GI side effects

  Control of intestinal Helminth infection

  Routine de-worming

  Nutrition education and promotion

  Promotion of exclusive breast-feeding (higher absorption)

  Education to delay the tea introduction to kids

  Fortification

  Ferrous sulfate is usually used to fortify infant formula and bread

  Example:

  Fortification of milk powder with Iron and Vit C in Chile

  Fortified cookies in school

  Flour fortification

THE END

References

WHO website