Eileen Whitehead 2010

East Lancashire HC NHS Trust

Urinalysis Testing Today -- Please Fill The Bottle

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What is the typical normal volume of urine ?

1-2 litres / 24 hours per normal adult, however,

the amount per day varies considerably

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The actual quantity is affected by factors such

as ?

Recent fluid intake

Recent food intake

Temperature

General Health

3

What are the physical characteristics of normal

urine ?

Volume is one main characteristics of urine.

Other physical characteristics that can apply to

urine include colour, turbidity (transparency),

smell and pH

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Colour:

Typically yellow-amber but varies according to

recent diet and the concentration of the urine.

Drinking more water generally tends to reduce

the concentration of urine, and therefore cause it

to have a lighter colour. (The converse is also

true)

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SOME COMMON CAUSES OF URINE DISCOLOURATION

COLOUR PATHOLOGICAL

CAUSE

FOOD AND DRUG

CAUSES

Brown Bile pigments Metronidazole

Fava Beans

Brown / Black Melanin Cascara

Green / Blue Pseudomonal UTI Amitriptyline

Orange Bile Pigments Phenothiazines

Red Haematuria Blackberries

Dark Yellow Concentrated Urine Carrots

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Turbidity:

Cloudy urine may be due to

Contamination with vaginal mucus

Pyruria secondary to infection

Hyperuricosuria (high protein diet)

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Smell:

Generally fresh urine has a mild smell but aged

urine has a stronger odour, similar to that of

ammonia. Diabetics may have a sweet or fruity

odour due to the presence of Ketones. Other

causes of abnormal odours are gastrointestinal

– bladder fistula (faecal smell) Vitamin B6 (Iron

smell) Asparagus (Sulphuric)

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Specific Gravity:

Urine specific gravity shows the concentration of

urine and represents the hydration status of the

patient. Normal specific gravity varies from 1.001

to 1.035. A greater value shows relative

dehydration, diabetes mellitus. A lower value

may indicate diabetes insipidus, increased fluid

intake, or decreased concentrating ability of the

kidney

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pH:

The pH of normal urine is generally in the range

4.6 - 8, a typical average being around 6.0.

Much of the variation is due to diet. For example,

high protein diets result in more acidic urine, but

vegetarian diets generally result in more alkaline

urine (both within the typical range 4.6 - 8).

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What is contained in normal urine ?

Approx. 95% of the volume of normal urine is

due to water. The other 5% consists of solutes

(chemicals that are dissolved in the water)

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Some of these solutes are the results of normal

biochemical activity within the cells of the body.

Other solutes may be due to chemicals that

originated outside of the body, such as

pharmaceutical drugs

1. Organic Molecules

2. Ions

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Organic molecules are electrically neutral and

can be relatively large (compared with the

'simpler' ions - below).

These include:

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Urea - Urea is an organic (i.e. carbon-based)

compound also known as carbamide. The

amount of urea in urine is related to quantity of

dietary protein

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Creatinine - Creatinine is a normal (healthy)

constituent of blood. It is produced mainly as a

result of the breakdown of creatine phosphate in

muscle tissue. It is usually produced by the body

at a fairly constant rate

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Uric acid - Uric acid is an organic (i.e. carbon-

based) Due to its insolubility, uric acid has a

tendency to crystallize, and is a common part of

kidney stones

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Ions are atoms or groups of atoms that have

either, lost some outer electrons, hence have a

positive electric charge, or have gained some

outer electrons and hence have a negative

electric charge

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Individual elements:

Sodium (Na+) and Potassium (K+) The amount

in urine varies with diet and the amount of

aldosterone (a steroid hormone in the body)

Chloride (Cl-) : The amount in urine also varies

with dietary intake

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Magnesium (Mg2+) : Amount in urine varies with

diet and the amount of parathyroid hormone in

the body. (Parathyroid hormone increases the

reabsorption of magnesium by the body, which

therefore decreases the quantity of magnesium

in urine)

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Calcium (Ca2+) : Amount in urine also varies

with diet and the amount of parathyroid hormone

in the body. (Parathyroid hormone increases the

reabsorption of calcium by the body, which

therefore decreases the quantity of calcium in

urine)

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WHY TEST URINE ?

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Urinalysis a useful procedure as an indicator of

health or disease, and as such, is a part of all

routine health screening

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Reagent dip-sticks can be used to test for the following chemicals in a fresh urine sample:

Leucocytes NitriteUrobilinogenProteinpHBloodSpecific GravityKetones BilirubinGlucose

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Leucocytes:

The presence of leucocytes in urine is an

important finding in inflammatory conditions of

the kidneys and urinary tract. In most cases,

where there is a bacterial UTI, leucocytes are

found in the urine

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Nitrates

Nitrate eliminated via the urinary tract only arise

due to the conversion of nitrate into bacteria

inside the urinary tract. Therefore one of the

most important symptoms of a bacterial UTI is

the presence of nitrate in the urine

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Urobilinogen

Urobilinogen is normally present in low

concentrations. It is formed in the intestine from

bilirubin, and a portion of it is absorbed back into

the bloodstream. When urobilinogen it could be

a sign of liver disease such as hepatitis and

cirrhosis. When urine urobilinogen is low or

absent, it can mean hepatic or biliary obstruction

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Protein

Healthy adults normally excrete 80-150 mg

protein in urine daily. However, detectible

proteinuria may be the first sign of renovascular,

glomerular or tubulo-interstitial renal disease.

Alternatively, it may be caused by overflow of

abnormal proteins in diseases such as myeloma

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Blood:

Haematuria the appearance of blood in the urine

most commonly presents in very small quantities

and is only detected by a simple dipstick test

Some of the causes of haematuria include

infection, tumours, trauma, inflammation, calculi

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Other possible causes of haematuria

1. Kidney cysts2. Tumours or kidney stones3. Blockages or stones in the tube to

the bladder4. Cystitis (bladder infection), 5. Bladder stones6. Tumours in the bladder7. Disease of the prostate gland

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Ketones:

Ketonuria is a condition where abnormally high

amounts of ketone bodies are present in the

urine. It is seen most commonly in uncontrolled

diabetes mellitus. However it may develop as a

result of fasting, dieting, starvation and eating

disorders

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Bilirubin

Bile (mainly conjugated bilirubin) is converted to

urobilinogen by intestinal bacteria. Most of the

urobilinogen is excreted in faeces or reabsorbed

and transported back to the liver to be converted

back into bile. The remaining urobilinogen (about

1% of total) is excreted in the urine.

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An elevated level of conjugated serum bilirubin

implies liver disease and can be an early feature

of hepatobiliary disease

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Glucose

Nearly all glucose filtered by the glomeruli is

reabsorbed in the proximal tubules, only

undetectable amounts appear in urine in healthy

patients

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There are two basic causes for glycosuria.

1. One is that the level of blood glucose is so high

that the renal tubules are unable to reabsorb all

that is presented

2. The other is a failure of the tubules to reabsorb

all glucose at a level where this should be

possible. The latter is called renal glycosuria

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If glycosuria occurs because a normal renal

threshold has been exceeded, this is usually

indicative of impaired glucose tolerance or frank

diabetes

It can occur in the non-diabetic if a substantial

amount of food high in sugar is consumed and

transiently overwhelms the insulin response

causing hyperglycaemia.

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HOW TO TEST URINE ?

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Urinalysis

Ensure that you have the correct equipment -

urine dipsticks, disposable gloves, apron and

sterile receiver

Obtain informed consent for procedure

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Explain to the patient how to take a mid-stream

urine sample:

Urine samples should be collected using 'clean-catch'

midstream sampling, which ensures that any bacteria

present in the urethra are washed away in the first

portion of urine (Higgins, 2000)

Catheter specimens of urine should be collected

using an aseptic technique in order to avoid

contamination (Higgins, 2000)

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Check manufacturer's recommendations

Check product expiry date

Wash hands and don gloves and apron

Collect specimen

Remove reagent dipstick and immediately

replace cap

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Dipstick urine

Immerse the dipstick into urine, then remove

(the duration that the dipstick remains in the

urine is governed by manufacturer's

recommendations)

Wait for appropriate length of time

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Wipe the edge of the strip against the rim of the

vessel in order to remove any excess urine.

Hold dipstick at a slight angle (This prevents

pad-to-pad contamination)

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Read the reagent pads against the reference

guide

Dispose of urine and dipstick as with

organisational policy

Remove gloves and apron.

Wash hands

Document results

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Any Questions?

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References

Dougherty, L., Lister, S. (2004) The Royal Marsden Hospital

Manual of Clinical Nursing Procedures. Oxford: Blackwell

Publishing.

Higgins, C. (2000) Microbiology testing. In: Understanding

Laboratory Investigations. Oxford: Blackwell Science

Urine Dipstick Analysis -http://www.patient.co.uk/DisplayConcepts.asp?WordId=URINALYSIS

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