Albumin Creatinine Ratio Calculator

Albumin Creatinine Ratio Calculator for Nephrology. KDIGO stratifies albuminuria into three bands: A1 normal-to-mildly increased (under 30 mg/g, under 3 mg/mmol), A2 moderately increased (30 to 300 mg/g, 3 to 30 mg/mmol; the range historically called microalbuminuria), and A3 severely increased (over 300 mg/g, over 30 mg/mmol; formerly macroalbuminuria). These bands are plotted against eGFR (G1 to G5) in the KDIGO green-yellow-orange-red heat map to grade combined risk of progression, cardiovascular events, and death. The albumin-risk relationship is continuous with no true threshold — risk rises measurably even within the A1 band — so A2 is an action trigger for renoprotective therapy, not merely a label, and rising UACR on treatment signals inadequate control while a falling ratio is an early efficacy marker.

How this calculator works

The urine albumin-to-creatinine ratio (UACR) divides urine albumin by urine creatinine measured in the same untimed (preferably first-morning) spot sample: dividing by creatinine corrects for how dilute or concentrated the specimen is, so a single random void can estimate 24-hour albumin excretion without a timed collection. Reporting units differ by region — mg/g in the US and mg/mmol in most of the world (mg/g divided by 8.84 gives mg/mmol). Because creatinine excretion tracks muscle mass, the same albumin leak yields a higher ratio in a low-muscle woman or elderly patient and a lower one in a muscular young man.

When to use this calculator

Use UACR to screen for and stage kidney damage in everyone with diabetes, hypertension, obesity, cardiovascular disease, or a family history of kidney failure, and to monitor response to ACE inhibitors, ARBs, SGLT2 inhibitors, and finerenone. It is the preferred albuminuria test over a plain dipstick or spot protein-to-creatinine ratio because it detects the low-grade albumin leak (A2 range) that a dipstick misses. Do not rely on a single elevated value: confirm a persistently high result on 2 of 3 samples over 3 to 6 months before diagnosing chronic albuminuria, and avoid testing during febrile illness, after heavy exercise, in overt urinary tract infection, during menstruation, or in decompensated heart failure, all of which transiently raise the ratio.

Inputs used

  • Urine albumin
  • Urine creatinine
  • Unit system

Clinical interpretation

KDIGO stratifies albuminuria into three bands: A1 normal-to-mildly increased (under 30 mg/g, under 3 mg/mmol), A2 moderately increased (30 to 300 mg/g, 3 to 30 mg/mmol; the range historically called microalbuminuria), and A3 severely increased (over 300 mg/g, over 30 mg/mmol; formerly macroalbuminuria). These bands are plotted against eGFR (G1 to G5) in the KDIGO green-yellow-orange-red heat map to grade combined risk of progression, cardiovascular events, and death. The albumin-risk relationship is continuous with no true threshold — risk rises measurably even within the A1 band — so A2 is an action trigger for renoprotective therapy, not merely a label, and rising UACR on treatment signals inadequate control while a falling ratio is an early efficacy marker.

Worked example

A 58-year-old man with type 2 diabetes returns a first-morning spot urine with albumin 45 mg/L and creatinine 90 mg/dL. Converting creatinine to grams: 90 mg/dL = 0.9 g/L, so UACR = 45 / 0.9 = 50 mg/g. This falls in the A2 (moderately increased) band. Combined with an eGFR of 70 mL/min/1.73 m2 (G2), his KDIGO cell is G2/A2 — moderately increased risk — which supports starting or up-titrating an ACE inhibitor or ARB plus an SGLT2 inhibitor and rechecking to confirm persistence.

Limitations and safety notes

The ratio is distorted whenever creatinine excretion is atypical: cachexia, amputation, or advanced age lower creatinine and inflate UACR, while high muscle mass or creatine supplementation deflates it, so the same category shift can mean different absolute albumin loss between patients. Non-first-morning samples run higher because of upright posture and activity; menstrual blood, symptomatic UTI, vigorous exercise within 24 hours, fever, and marked hyperglycemia all cause transient false elevations. UACR reflects glomerular albumin leak specifically and will miss tubular or overflow proteinuria (for example Bence Jones protein in myeloma), where a total protein-to-creatinine ratio is needed instead.

Frequently asked questions

Is albumin-to-creatinine ratio the same as the old microalbuminuria test?

The A2 band (30 to 300 mg/g) corresponds to what was historically called microalbuminuria, but KDIGO abandoned the micro/macro terminology because it wrongly implied a hard threshold. UACR treats albuminuria as a continuous risk marker, and the A1/A2/A3 bands are used instead.

Do I need a 24-hour urine collection instead?

For most screening and monitoring a first-morning spot UACR replaces the cumbersome 24-hour collection with comparable prognostic value. A timed collection is reserved for unusual cases where the spot ratio and clinical picture disagree, or when precise quantification is needed.

Why did my result change so much between two visits?

Day-to-day biological variability in albuminuria is large, and posture, exercise, hydration, fever, and glycemic control all shift the number. This is exactly why KDIGO requires confirming an abnormal result on 2 of 3 samples over 3 to 6 months rather than acting on a single value.

How do I convert between mg/g and mg/mmol?

Divide the mg/g value by 8.84 to get mg/mmol (or multiply mg/mmol by 8.84 to get mg/g). So 30 mg/g equals about 3.4 mg/mmol and 300 mg/g equals about 34 mg/mmol, which is why the international A2 and A3 cutoffs are cited as 3 and 30 mg/mmol.

Can the ratio be normal but kidney disease still be present?

Yes. UACR detects glomerular albumin leak but can be normal in tubulointerstitial disease, obstruction, or overflow proteinuria such as myeloma light chains. If suspicion remains, pair UACR with eGFR and a total protein-to-creatinine ratio.

References

  • Chronic Kidney Disease Prognosis Consortium; Matsushita K, van der Velde M, Astor BC, et al. Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis. Lancet. 2010. PMID: 20483451.
  • Fox CS, Matsushita K, Woodward M, et al. Associations of kidney disease measures with mortality and end-stage renal disease in individuals with and without diabetes: a meta-analysis. Lancet. 2012. PMID: 23013602.
  • Grams ME, Coresh J, Matsushita K, et al. Estimated Glomerular Filtration Rate, Albuminuria, and Adverse Outcomes: An Individual-Participant Data Meta-Analysis. JAMA. 2023. PMID: 37787795.
  • Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. 2024.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: April 23, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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