should be free from even traces of protein compounds. Sample Collection and Preparation For Qualitative Method Though random urine specimens can be used, first

 

¾ In diabetic patients for early diagnosis of nephropathy

¾ In hypertensive patients as indicator of end organ

damage associated with lower life expectancy, and

¾ Is probably associated with cardiovascular diseases in

general population.

Microalbuminuria Detection

It is recommended in the following subjects:

Diabetic Subjects:

¾ Insulin-dependent diabetes mellitus (IDDM): Annually

in all patients suffering from diabetes for 5 years or

more and over 12 years of age

¾ Non-insulin dependent diabetes mellitus (NIDDM): As

soon as diabetes is diagnosed, and at regular intervals

(1–2 times) annually thereafter in case of negative test

results.

Nondiabetic Subjects:

¾ All patients with potential disease involvement of the

kidneys for early diagnosis

¾ Patients at risk of cardiovascular complications.

Microalbuminuria Indirect Latex Slide Test, Microtex®

(Courtesy: Tulip Group of Companies)

Summary

Urinary albumin excretion between 30–300 mg/day (micro -

albuminuria), far below the levels found in clinical proteinuria

(> 300 mg/day) is a strong predictor of development of

diabetic nephropathy and vascular complications. These low

levels of albumin excretion are detectable only by sensitive

immunoassays for microalbuminuria.

Diabetic nephropathy leads to progressive loss of renal

function or end-stage renal disease (ESRD) and may

necessitate need for dialysis or transplantation in most

cases. The progression of microalbuminuria is closely

associated with progressive hypertension and loss of blood

glucose control. The early presence of microalbuminuria

can be reversed by strict metabolic control and timely

intervention of drugs early in the course of disease can

arrest the progression of diabetic renal disease. Annual

screening of microalbuminuria is recommended by the

‘WHO’ and ‘International Diabetes Foundation’ in all

patients with IDDM over the age of 12 years and who have

had diabetes for 5 years or more.

Microalbuminuria is also a significant risk marker of

cardiovascular diseases. Its presence can be regarded as

an index of increased cardiovascular vulnerability and a

signal for correction of known risk factors.

Microtex is a sensitive immunoassay useful for the

detection of microalbuminuria.

Reagent

1. Antihuman albumin reagent: The concentration

of antibodies to human albumin is adjusted to

provide sensitivity of about 25 mg/L and above of

microalbuminuria.

2. Albumin latex reagent: A uniform suspension of

polystyrene latex particles to which human albumin

has been chemically coupled. Each batch of reagent

undergoes rigorous quality control at various stages

of manufacture for its specificity, sensitivity and

performance.

Reagent Storage and Stability

Store the reagents at 2–8°C. Do not freeze.

The shelf life of the reagents is as per the expiry date

mentioned on the reagent vial labels.

Principle

Microtex slide test for the detection of microalbuminuria

is based on the principle of agglutination inhibition. The

urine specimen to be tested is first mixed with antibody

reagent containing antibodies directed against human

albumin. The latex coupled with human albumin is

added to the mixture and is allowed to react. When the

urine specimen does not contain albumin, antibodies

to human albumin would be free to react with the latex

coupled with human albumin causing agglutination.

When the urine specimen contains at least 25 mg/L

of albumin, the antibodies to human albumin will be

neutralized and will not be available to react with latex

couple with human albumin. Hence, no agglutination

will be observed.

64 Concise Book of Medical Laboratory Technology: Methods and Interpretations Note

1. In vitro diagnostic reagent for laboratory and professional use only. Not for medicinal use.

2. All the materials derived from human source have

been tested for HBsAg and anti-HIV antibodies and

found to be nonreactive.

3. The reagents contain 0.1% sodium azide as preservative.

Avoid contact with skin or mucosa. On disposal, flush

with large quantities of water.

4. The reagents can be damaged due to microbial

contamination or on exposure to extreme temperatures.

It is recommended that the performance of reagents

shouldbe verified with positive and negative controls

provided with the kit.

5. Use reagents of same lot numbers. Do not interchange

reagents of different lot numbers.

6. Do not interchange vial droppers.

7. Shake the albumin latex reagent vial well before use

to disperse the latex particles uniformly and improve

test readability.

8. Only a clean and dry glass slide must be used. Slide

should be free from even traces of protein compounds.

Sample Collection and Preparation

For Qualitative Method

Though random urine specimens can be used, first

morning urine specimen is preferable. Specimens should

be collected in clean glass or plastic containers free of

detergents. Specimens should be tested immediately

preferably within 12 hours of collection. Should a delay

in testing occur, add thimerosal (0.01%) or sodium azide

(0.1%) to the specimen and store at 2–8°C up to 72 hours.

Do not use grossly contaminated specimens. If specimen

is cloudy or contains blood, centrifuge the specimen at

1000 rpm (revolutions per minute) for one minute and use

clear supernatant for testing.