ACR Calculator
Calculate Urine Albumin-to-Creatinine Ratio (ACR) to assess kidney damage and stage CKD per KDIGO 2024 guidelines. Free online nephropathy screening tool.
About This Calculator
The ACR (Albumin-to-Creatinine Ratio) Calculator is a free online screening tool that computes the ratio of albumin to creatinine in a spot urine sample to detect early kidney damage (nephropathy). Chronic kidney disease (CKD) affects approximately 10-15% of the global population, and ACR is one of the most important screening tests recommended by the KDIGO (Kidney Disease: Improving Global Outcomes) guidelines. This calculator helps patients with diabetes, hypertension, cardiovascular disease, or a family history of kidney disease assess their albuminuria status quickly and accurately from their lab results.
The ACR is calculated using the formula: ACR (mg/g) = Urine Albumin (mg/dL) × 1000 / Urine Creatinine (mg/dL). The result is classified into three categories per KDIGO 2024 guidelines: A1 (normal to mildly increased, <30 mg/g), A2 (moderately increased, 30–300 mg/g), and A3 (severely increased, >300 mg/g). Persistent ACR ≥30 mg/g on three tests over three months confirms chronic kidney disease. The ACR is more sensitive than total protein dipstick testing for detecting early diabetic nephropathy because it specifically measures albumin, the first protein to appear in urine when the glomerular filtration barrier is damaged.
The ACR test requires only a spot urine sample — ideally the first morning void after proper genital cleaning. Unlike 24-hour urine collection, the spot ACR is convenient and correlates well with timed collections. However, ACR can be affected by factors such as exercise, fever, urinary tract infection, menstrual bleeding, and extreme hydration levels, so confirmatory testing is essential before diagnosis. The ACR is combined with eGFR (estimated glomerular filtration rate) on the KDIGO heat map to create a comprehensive CKD prognosis staging system with 15 risk categories.
Regional Notes
India: CKD affects approximately 17% of the Indian population, with diabetes and hypertension being the leading causes. ICMR guidelines recommend annual ACR screening for all diabetics and hypertensives over 40 years of age. The test costs ₹200-500 at accredited labs and is included in the National Programme for Prevention and Control of Non-Communicable Diseases (NP-NCD) screening protocols. Major diagnostic chains like Dr. Lal PathLabs, Metropolis, and Thyrocare offer ACR testing.
United States: The US Preventive Services Task Force recommends CKD screening for adults with diabetes or hypertension. Medicare covers annual ACR testing for patients with diabetes as part of the Medicare Diabetes Prevention Program. The American Diabetes Association (ADA) Standards of Care recommend annual ACR testing for all type 2 diabetics and type 1 diabetics with duration over 5 years. The test costs $20-100 and is widely available at LabCorp, Quest Diagnostics, and hospital labs.
United Kingdom: NICE guidelines recommend ACR testing as the first-line test for proteinuria detection in primary care. The NHS Diabetes Prevention Programme includes annual ACR screening for all diabetics and hypertensives. The test is performed free of charge at GP surgeries and hospital labs across the UK. NICE recommends ACR over protein:creatinine ratio (PCR) for diabetic patients due to higher sensitivity for low-level albuminuria.
Frequently Asked Questions
What is ACR in medical terms?
ACR stands for Albumin-to-Creatinine Ratio, calculated from a spot urine sample by dividing urine albumin (mg/dL) by urine creatinine (g/dL). Normal ACR is below 30 mg/g (A1 category). Values between 30-300 mg/g indicate moderately increased albuminuria (A2), and values above 300 mg/g indicate severely increased albuminuria (A3). ACR is the preferred test for detecting early kidney damage per KDIGO 2024 guidelines.
How is the ACR calculated?
The ACR (Albumin-to-Creatinine Ratio) is calculated using the formula: ACR (mg/g) = Urine Albumin (mg/dL) × 1000 / Urine Creatinine (mg/dL). For example, if urine albumin is 8 mg/dL and creatinine is 110 mg/dL (0.11 g/dL), then ACR = 8 × 1000 / 110 = 72.7 mg/g, which falls in the moderately increased A2 category.
Who should get an ACR test?
KDIGO guidelines recommend annual ACR screening for all adults with diabetes (type 1 or type 2), hypertension, cardiovascular disease, age over 60, family history of chronic kidney disease (CKD), and those taking nephrotoxic medications. In India, the ICMR recommends ACR screening for all diabetics and hypertensives over age 40. The US Preventive Services Task Force recommends screening for at-risk adults aged 50-75.
How is ACR different from urine protein test?
ACR specifically measures albumin, the smallest and most abundant protein in urine, making it more sensitive than total protein dipstick tests for detecting early kidney damage. ACR can detect microalbuminuria (30-300 mg/g) that total protein tests miss. The protein-to-creatinine ratio (PCR) is used when total protein measurement is needed, but ACR is preferred for diabetic nephropathy screening per KDIGO guidelines.
How often should ACR be tested?
For initial screening, annual ACR testing is recommended for at-risk individuals. If the result is abnormal (A2 or A3), repeat testing is recommended within 3 months. CKD diagnosis requires three elevated ACR tests over 3 months. For patients with confirmed CKD, ACR should be monitored every 3-12 months depending on disease severity. More frequent monitoring is recommended for patients on ACE inhibitors, ARBs, or nephrotoxic medications.
What does ACR A1, A2, A3 mean?
ACR is classified into three categories per KDIGO guidelines. A1 (normal to mildly increased) is ACR below 30 mg/g indicating normal kidney function. A2 (moderately increased, formerly microalbuminuria) is ACR 30-300 mg/g indicating early kidney damage requiring intervention. A3 (severely increased, formerly macroalbuminuria) is ACR above 300 mg/g indicating significant kidney damage. These categories combine with GFR stages (G1-G5) to determine CKD prognosis.
Can ACR help monitor CKD progression?
Yes, ACR is a key marker for monitoring CKD progression. The KDIGO heat map uses both ACR (A1-A3) and eGFR (G1-G5) to create 15 prognostic stages. A rising ACR over time indicates worsening kidney damage and faster disease progression. Treatment goals include reducing ACR through blood pressure control, ACE inhibitors or ARBs, SGLT2 inhibitors, and glycemic control in diabetics. A 30% or greater reduction in ACR is considered clinically significant.
How much does an ACR test cost?
In India, an ACR test typically costs ₹200-500 at diagnostic labs, often included in diabetes complication screening packages. In the United States, the test costs $20-100 and is covered by Medicare Part B and most insurance plans for at-risk patients. In the United Kingdom, the NHS provides ACR testing free of charge as part of routine diabetic and hypertensive care. The test requires only a spot urine sample with no special preparation needed.