What this test measures
Microalbumin measures albumin in the urine at levels too low for a standard urine dipstick to detect. Healthy kidneys excrete almost no albumin; even a small leak is an early signal of glomerular damage. The preferred test today is the urine albumin-creatinine ratio (UACR) on a spot urine sample — it corrects for hydration and avoids the inconvenience of a 24-hour collection.
Results are reported as mg/g or mg/mmol creatinine. KDIGO defines three categories: A1 normal (<30 mg/g), A2 moderately increased ("microalbuminuria", 30–300 mg/g), A3 severely increased ("macroalbuminuria", >300 mg/g).
Why it matters
In India, diabetic kidney disease is the leading cause of CKD and end-stage renal disease. Microalbuminuria is the earliest detectable signal — it appears years before eGFR falls and is reversible at this stage with tight blood-sugar control, ACE inhibitor / ARB therapy, SGLT2 inhibitors, and blood-pressure control. Once macroalbuminuria sets in, progression to CKD is harder to stop.
The American Diabetes Association and KDIGO both recommend annual UACR for all adults with diabetes (and most with hypertension or family history of CKD). It is a cheap, simple test that catches treatable kidney disease at its most reversible stage — but is widely under-used in Indian outpatient practice.
How to prepare
A first morning spot urine sample is preferred. No fasting required. Avoid vigorous exercise in the 24 hours before (transient albuminuria can occur). Do not collect during menstruation or active urinary infection — both falsely raise albumin. Drink normally; do not overhydrate.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Urine Albumin-Creatinine Ratio (UACR) (mg/g creatinine)[1][2] | A1 < 30 (normal) · A2 30 – 300 (moderately increased) · A3 > 300 (severely increased) | Low / normal UACR is reassuring but does not rule out kidney disease if eGFR is reduced — both tests are complementary. | 30 – 300 mg/g — moderately increased albuminuria (microalbuminuria) — early diabetic kidney disease, hypertensive nephropathy, early glomerular disease. >300 mg/g — severely increased (macroalbuminuria) — established kidney disease; consider nephrology referral. Persistent values >2200 mg/g (nephrotic range) — nephrotic syndrome — needs urgent evaluation. |
KDIGO albuminuria categories and action
| Category | UACR (mg/g) | Description | Action |
|---|---|---|---|
| A1 | < 30 | Normal to mildly increased | Annual screening in diabetes / HTN |
| A2 | 30 – 300 | Moderately increased (microalbuminuria) | Confirm on a second sample; start / optimise ACE inhibitor or ARB; tight BP and glycaemic control; consider SGLT2 inhibitor; recheck quarterly |
| A3 | > 300 | Severely increased (macroalbuminuria) | Confirm on a second sample; full nephrology workup; aggressive BP / glycaemic control; SGLT2 inhibitor; consider referral |
| Nephrotic range | > 2200 | Heavy proteinuria | Urgent nephrology referral; consider biopsy |
Frequently asked questions
Why use the albumin-creatinine ratio instead of a plain urine albumin?
Albumin concentration alone varies with how dilute or concentrated the urine is. Dividing by creatinine (which is excreted at a fairly constant rate) gives a hydration-independent value that correlates well with a 24-hour albumin excretion — without the hassle of a 24-hour collection.
Do I need to fast?
No fasting required. A first morning spot urine sample is preferred. Avoid testing during menstruation, urinary infection, or just after heavy exercise.
My UACR is 50 mg/g. What does that mean?
You are in the A2 / "microalbuminuria" range — early kidney damage. This is reversible if treated. Your doctor will repeat the test (transient causes need to be excluded), then optimise blood pressure, glycaemic control, start an ACE inhibitor or ARB and possibly an SGLT2 inhibitor.
How often should I get a microalbumin test?
Annually for all adults with diabetes (from diagnosis in type 2, from 5 years in type 1), for hypertensives, and for anyone with a family history of CKD. Every 3–6 months if a previous test was abnormal or you are on treatment for diabetic kidney disease.
Can exercise cause microalbuminuria?
Yes — heavy exercise can cause transient albuminuria for 24–48 hours. Avoid vigorous exercise the day before the test.
Will treatment cure microalbuminuria?
Yes, it can — that is why we test. Tight blood-pressure control, ACE inhibitors / ARBs, SGLT2 inhibitors, glycaemic control and (for some patients) a low-salt diet can reduce or eliminate microalbuminuria and slow progression to CKD.
Is a 24-hour urine collection still useful?
Rarely. The spot UACR is recommended in most cases. A 24-hour collection is reserved for special situations (atypical results, evaluation before kidney biopsy, or very heavy proteinuria where exact quantification matters).
Related Kidney / Electrolytes tests
Tests commonly ordered alongside URINARY MICROALBUMIN, or that help interpret an unexpected result.
Sources & references
- KDIGO 2024 CKD Clinical Practice Guideline · accessed 2026-05-30T00:00:00.000Z
- American Diabetes Association — Standards of Care 2024 · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Urine Albumin Test · accessed 2026-05-30T00:00:00.000Z
- Indian Society of Nephrology — CKD Guidelines · accessed 2026-05-30T00:00:00.000Z
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