Microalbuminuria

Sample for Microalbuminuria

1. The sample is urine.
2. It is better to do three random samples for a week.
3. The urine sample is stable at room temperature for up to 2 days and at 8 °C for up to 14 days.

Indications for Microalbuminuria

1. This is advised in a diabetic patient to rule out diabetic nephropathy; even routine urine tests are negative.
2. High-risk patients should be tested within a 3 to 6 months period.
3. Check-in the case of hypertensive patients.

Precautions for microalbuminuria

1. Avoid urine after exercise.
2. Avoid prolonged upright posture.
3. Avoid in case of hematuria.
4. Avoid blood-contaminated urine.
5. Avoid in case of genitourinary tract infection.
6. Avoid in case of congestive heart failure.
7. Avoid in case of uncontrolled hyperglycemia or hypertension.

False positive microalbuminuria

1. Can get false positive results in case when pH urine ≥8.0.
2. When the temperature is >77 °F.
3. When Tamm-Horsfall protein is present in the urine.

Pathophysiology of Microalbuminuria

1. Microalbumin is a misnomer. This does not refer to any different form of albumin; instead, a small amount of albumin is excreted in the urine.

Definition of microalbuminuria:

1. Microalbuminuria is defined as persistent that is below the detection by routine reagent strips but greater than normal.
   1. This is defined as the excretion of 30 to 150  µg/min protein in the urine and is not detected by dipsticks but can be measured by sensitive methods.
   2. Microalbuminuria is predictive of diabetic nephropathy.
2. Diabetic microalbuminuria definition:
   1. Albumin excretion of 20 to 200 µg/minute (30 to 300 mg/24 hours) detected 2/3 determinations done in the last 6 months.
   2. Microalbuminuria may be found in non-diabetic hypertensive patients.
3. The subclinical state of selectively elevated albumin excretion rate is called microalbuminuria.

4. Normally the small amount is excreted by the glomeruli, which is reabsorbed by the tubules.

5. When the disease increases, the albumin excreted by the glomeruli is more than reabsorbed by the tubule will lead to microalbuminuria which is not detected by ordinary methods.
   3. There are structural changes in the glomeruli leading to increased glomerular permeability.
   4. Increased glomerular permeability leads to increased urinary exertion of proteins like albumin and IgG.
   5. Albumin remains in the normal range in the first 5 years of diabetes mellitus type 1 diagnosis.
6. This urinary albumin excretion precedes and is highly indicative of diabetic nephropathy and is called microalbuminuria.
   1. Early detection of microalbumin may predict end-stage renal nephropathies in Diabetes type 1 (IDDM) patients.
7. This test is useful for diagnosing Angiopathic changes in diabetic patients before gross proteinuria is seen.
8. Evidence suggests that lowering blood pressure and controlling hyperglycemia will alter the disease’s course and prevent irreversible nephropathy.

Microalbuminuria is the first sign of diabetes complications like:

1. Diabetic nephropathy.
2. Cardiovascular diseases.
3. Myocardial infarction.
4. Hypertension.
5. Stroke.
6. Kidney failure.
7. Diabetic patients with microalbuminuria have 5 to 10 times more chances for cardiovascular mortality, retinopathy, and end-stage kidney.
8. The presence of microalbuminuria in nondiabetic patients is an indicator of lower life expectancy because of hypertension and cardiovascular disease risk.
9. Nondiabetic nephropathies may show microalbuminuria.

Recommendations for microalbuminuria in diabetic patients are:

1. Diabetic patients should have an annual checkup of microalbuminuria (3 to 6 months period).
2. if 2 out of 3 measurements are >20 mg/L, start the treatment (intervention).

Interpretation of the microalbuminuria:

1. Albumin/creatinine ratio >30 mg/g predicts an overnight excretion rate of 30 µg/minute.
2. Albuminuria <0.3 g/day will be detected only by sensitive methods like nephelometry or electrophoresis.

Normal Albumin in the urine 

Source 1

• Albumin in urine < 30 mg/24 hours
• Or < 20 mg/day.
• Or < 20 mg/L (urine collected in 10 hours).

Source 2 

• 0.2 to 1.9 mg/dL

 Abnormal value 

• Albumin > 30 mg/24 hours.
• Or > 20 mg/L (in 10 hours).

Limits with various dipsticks:

1. Albusure 2 to 3 mg/dl
2. Micral 1.5 to 2 mg/dl
3. Micro-Burnintest 4 to 8 mg/dl

Microalbuminuria is seen in:

1. Diabetes mellitus.
2. Myoglobinuria.
3. Nephrotoxic drugs.
4. Bence-Jones proteinuria.
5. Hemoglobinuria.
6. Any kind of Nephropathy.
7. Hypertension.
8. Myocardial infarction.
9. Atherosclerosis ( Generalized vascular disease ).
10. Lipid abnormalities.
11. Pre-eclampsia.