has classically been an important sign in the diagnosis of pre-eclampsia.^(2,3) However, customary dipstick methods for detecting proteinuria fail to detect minimal elevations in urinary excretion of albumin that maybe present before other clinical signs and symptoms of pre-eclampsia. With the recent development of the Indirect Latex Slide Test for detection of microalbuminuria, it is now possible to detect minimal elevations in albumin excretion that would have gone unnoticed in the past. Microalbuminuria is defined as excretion of minute amount of urinary albumin concentration between 30-300 mg/litre and urinary albumin excretion rate of 20-200 µg/min, which is usually not detectable by routine screening methods.^(4,5) Till it manifests overtly as proteinuria-a condition where significant kidney damage has already occurred.

MATERIALS AND METHODS

The study group consisted of 200 pregnant women at 18-22 weeks of gestation, free of signs and symptoms of pre-eclampsia, and pregnancy-induced hypertension. They were registered into the study at random from Outpatient Clinic of Obstetrics Department of Government Kasturba Gandhi Hospital, Chennai.

Inclusion Criteria

200 pregnant women at 18-22 weeks of gestation, free of signs and symptoms of pre-eclampsia, and pregnancy-induced hypertension.

Exclusion Criteria

a)       Past history of chronic hypertension, diabetes, renal disease.

b)      Presence of urinary tract infection.

c)       Presence of genital tract infection.

d)      BP ≥140/90 mmHg at the time of gestation.

e)       Presence of proteinuria by customary dipstick method.

All these Patients had Completed their Initial Evaluation like

a)   Complete history.

b)   General examination-BP was measured after 5 minutes in the supine position and oedema evaluated clinically.

c)    Per abdominal examination.

d)   Routine blood investigations.

e)   Urine examination-routine and microalbuminuria.

METHODS

At each clinical visit, a random clean catch sample of urine was collected in a sterile glass bottle without any preservative and analysed for microalbuminuria by indirect latex slide test. Standardisation of microalbumin estimation was done in 50 nonpregnant normotensive women of similar age and parity. Microalbumin excretion was expressed as mg/ltr. and was taken positive when microalbumin excretion was 25 mg/ltr. The concentration of urine microalbumin was established by the indirect latex slide test.

Reagent

1. Anti-human albumin reagent: The concentration of antibodies to human albumin is adjusted to provide sensitivity of about >=25 mg/litre and above of microalbuminuria.
2. Albumin latex reagent: A uniform suspension of polystyrene latex particles to which human albumin has been chemically coupled.

Principle of Indirect Latex Slide Test

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 latex coupled with human albumin causing agglutination. When the urine specimen contains at least 25 mg/litre of albumin, the antibodies to human albumin will be neutralised and not available to react with latex coupled with human albumin. Hence, no agglutination will be observed.

Sample Collection and Preparation

Specimen collected in clean glass or plastic containers free of detergents. Specimen tested preferably within 12 hrs. of collection.

If delay in testing occurs thiomersal (0.01%) added to the specimen and stored at 2-8°c up to 72 hours.

Test Procedure

1. All reagents and samples are brought to room temperature before use.
2. One drop of clear urine under test is placed vertically on the glass slide.
3. One drop of antihuman albumin reagent is added to the drop of urine under test.
4. The antihuman albumin and reagent is mixed over the circle for 30 seconds.
5. One drop of well mixed albumin latex reagent is added to the mixture uniformly over the entire circle.
6. The slide is rocked gently back and forth observing for agglutination macroscopically at 3 minutes.

Interpretation of Results

Agglutination-negative test indicating absence of detectable levels of albumin in urine signifying absence of microalbumin.

No agglutination-positive test indicating presence of albumin in concentration of above 25 mg/litre in urine signifying microalbuminuria.

The urinary microalbumin estimation was done minimum 3 times during pregnancy at 18-22 wks., 23-28 wks., and 29-34 wks. All subjects received antenatal care and were followed for occurrence of hypertensive disorder.

RESULTS

Of the 200 subjects, 186 could be followed up. Out of 186 subjects who went to term and in which outcome could be known, 41 (22.35%) developed hypertensive disorder (PIH, Pre-eclampsia, Transient hypertension). Of these 41 women, 23 (12.30%) had PIH, 10 (5.20%) pre-eclampsia, and 8 (4.71%) developed transient hypertension. At 18-22 weeks, 4.96% were microalbuminuria positive 66% of them and out of microalbuminuria negative 20% developed hypertensive disorder. By 29-34 weeks of gestation, 96.76% were microalbuminuria positive, 23.75% of them and 18% of microalbumin negative also developed hypertensive disorder by term. Analysis of variance of microalbuminuria positivity with socioeconomic status, height, past gestational complications, Hb, and blood group was found to be nonsignificant, but with weight was significant. Gravidity was found to be a statistically significant variable. Microalbuminuria estimation around 18 weeks seems to be a useful predictor especially in heavier women and primigravidas.^(6,7,8) The sensitivity of microalbuminuria in predicting the development of PE was 60%, specificity 96.9%, Positive Predictive Value (PPV) 66.6%, and Negative Predictive Value (NPV) 80%. It may be concluded that early pregnancy levels of microalbuminuria can be used as predictors of pre-eclampsia with high negative predictive value.^(9,10)

Out of 200 Subjects included at 18-22 Weeks

• 186 women could be investigated by 23-28 weeks.
• 2 women aborted.
• 12 women were lost to follow up.
• 186 samples could be analysed serially by 29-34 weeks. These 186 subjects were further followed.

Out of the 186 Subjects

1. 145 women (77.65%) remained normotensive.

2. 41 women (22.35%) developed hypertensive disorder.

Pattern of HT Disorders in Microalbuminuria Tested Patients

Of the 41 women (22.35%) developed hypertensive disorder.

1. 23 women (12.3%) developed Pregnancy-Induced Hypertension (PIH).
2. 10 women (5.2%) developed Pre-eclampsia.
3. 8 women (4.7%) developed Transient hypertension.

Out of the 33 (17.7%) Women with (PIH)/Pre-eclampsia

1. 23 women (12.5%) had Pregnancy-Induced Hypertension (PIH).
2. 7 women (4.1%) had mild Pre-eclampsia.
3. 3 women (1.1%) had severe Pre-eclampsia.

Observations in Microalbuminuria Tested

Patients at 18-22 Weeks of Gestation. At 18-22 Weeks:

1. 9 women (4.96%) were microalbumin positive. Of these;
2. 3 women (33%) remained normotensive.
3. 6 women (66%) developed hypertensive disorder.
   1. 177 women (95.04%) were microalbuminuria negative. Of these;
   2. 142 women (80%) remained normotensive.
   3. 35 women (20%) developed hypertensive disorder.

Observations in Microalbuminuria Tested

Patients at 23-28 Weeks of Gestation. By 23-28 weeks:

1. 65 women (34.92%) were microalbumin positive. Of these;
2. 40 women (62%) remained normotensive.
3. 25 women (38%) developed hypertensive disorder.
   1. 121 women (65.18%) were microalbuminuria negative. Of these;
   2. 107 women (88.2%) remained normotensive.
   3. 14 women (11.8%) developed hypertensive disorder.

Observations in Microalbuminuria Tested

Patients at 29-34 Weeks of Gestation. By 29-34 Weeks:

1. 180 women (96.76%) were microalbumin positive. Of these;
2. 137 women (76.25%) remained normotensive.
3. 43 women (23.75%) developed hypertensive disorder.
   1. 6 women (3.24%) were microalbuminuria negative. Of these;
   2. 5 women (82%) remained normotensive.
   3. 1 woman (18%) developed hypertensive disorder.

Observation in Microalbuminuria Tested Patients at Various Weeks of Gestation in Relation to Age

Analysis of variance for microalbuminuria positivity and age was found to be significant. (p <0.001). The microalbuminuria and hypertensive disorders was more in the extremes of age (18-19 yrs. and 28-33 yrs.) at 18-22 weeks of gestational age.

Observations in Microalbuminuria Tested Patients at 18-22 Weeks of Gestation in Relation to Age at 18-22 Weeks

In the age group of 18-22 years-Out of 65 women:

1. 3 women were microalbumin positive. Of these;
   1. Women remained normotensive.
   2. Women developed hypertensive disorder.
2. 62 women were microalbuminuria negative. Of these;
3. 59 women remained normotensive.
4. 3 women developed hypertensive disorder.

In the age group of 23-27 years-Out of 80 women:

1. 1 woman were microalbumin positive and developed hypertensive disorder.
2. 79 women were microalbuminuria negative. Of these;
3. 77 women remained normotensive.
4. 2 women developed hypertensive disorder.

In the age group of 28-33 years-Out of 41 women.

1. 5 women were microalbumin positive. Of these;
2. 2 women remained normotensive.
3. 3 women developed hypertensive disorder.
   1. 36 women were microalbuminuria negative. Of these;
   2. 6 women remained normotensive.
   3. 30 women developed hypertensive disorder.

Observations in Microalbuminuria Tested Patients at Various Weeks of Gestation in Relation to Gravidity

Gravidity was found to be statistically significant variable. More microalbuminuric primigravida developed hypertensive disorder. (p <0.001).

Observations in Microalbuminuria Tested Patients at 18-22 Weeks of Gestation in Relation to Gravidity at 18-22 Weeks

In gravida 1-Out of 94 women:

1. 7 women were microalbumin positive. Of these;
2. 3 women remained normotensive.
3. 4 women developed hypertensive disorder.
   1. 87 women were microalbuminuria negative. Of these;
   2. 71 women remained normotensive.
   3. 16 women developed hypertensive disorder.

In gravida 2-Out of 65 women:

1. None of the women were microalbumin positive.
2. 65 women were microalbuminuria negative. Of these;
3. 56 women remained normotensive.
4. 9 women developed hypertensive disorder.

In gravida 3 and above-Out of 27 women:

1. 2 women were microalbumin positive and all of them developed hypertensive disorder.
2. 25 women were microalbuminuria negative. Of these;
3. 15 women remained normotensive.
4. 10 women developed hypertensive disorder.

Observations in Microalbuminuria Tested Patients at Various Weeks of Gestation in Relation to Maternal Weight

Analysis showed maternal weight as an independent variable with microalbuminuria for predicting hypertensive disorder at 18-22weeks.

Observations in Microalbuminuria Tested Patients at 18-22 Weeks of Gestation in Relation to Maternal Weight at 18-22 Weeks

In women weighing45-49 kg-Out of 19 women:

1. 2 women were microalbumin positive. Of these;
2. 1 women remained normotensive.
3. 1 women developed hypertensive disorder.
   1. 17 women were microalbuminuria negative. Of these;
   2. 15 women remained normotensive.
   3. 2 women developed hypertensive disorder.

In women weighing 50-54 Kg-Out of 135 women:

1. 7 women were microalbumin positive. Of these;
2. 2 women remained normotensive.
3. 5 women developed hypertensive disorder.
   1. 128 women were microalbuminuria negative. Of these;
   2. 102 women remained normotensive.
   3. 26 women developed hypertensive disorder.

In women weighing>55 Kg-Out of 32 women.

All women were microalbuminuria negative. Of these;

1. 25 women remained normotensive.
2. 7 women developed hypertensive disorder.

Observations in Microalbuminuria Tested Patients at Various Weeks of Gestation in Relation to Platelet Count

Platelet count <1.5 lakhs/cubic. mm was found to be correlated to microalbuminuria significantly at 18-22 weeks (P <0.001>).

Observations in Microalbuminuria Tested Patients at 18-22 Weeks of Gestation in Relation to Platelet Count at 18-22 Weeks.

In women with platelet count ≤1.5 lakhs/cubic. mm-Out of 22 women:

1. 7 women were microalbumin positive. Of these;
2. 3 women remained normotensive.
3. 4 women developed hypertensive disorder.
   1. 15 women were microalbuminuria negative. Of these;
   2. 10 women remained normotensive.
   3. 5 women developed hypertensive disorder.

In women with platelet count 1.5-1.9 lakhs/cubic. mm-Out of 159 women:

1. 1 woman was microalbumin positive and developed hypertensive disorder.
2. 158 women were microalbuminuria negative. Of these;
   1. 130 women remained normotensive.
   2. 28 women developed hypertensive disorder.

In women with platelet count ≥2 lakhs/cubic.mm-Out of 5 women:

1. 1 woman was microalbumin positive and developed hypertensive disorder.
2. 4 women were microalbuminuria negative. Of these;
3. 2 women remained normotensive.
4. 2 women developed hypertensive disorder.

Statistical analysis showed no correlation between socioeconomic status, past gestational complications, height, haemoglobin, or blood group with microalbuminuria positivity.