Albumin-Creatinine Ratio
Also known as: ACR, UACR
What Does Albumin-Creatinine Ratio Measure?
The Albumin-to-Creatinine Ratio (ACR), also known as the Urine Albumin-to-Creatinine Ratio (UACR), measures the amount of albumin (a protein made by the liver) relative to creatinine (a waste product from muscle metabolism) in a urine sample. Because urine concentration can vary throughout the day depending on hydration levels, dividing the albumin level by the creatinine level corrects for this variability, providing a more accurate and reliable estimate of how much albumin is being excreted in the urine over a 24-hour period — without requiring a cumbersome timed urine collection.
Why Does Albumin-Creatinine Ratio Matter?
Healthy kidneys filter waste while retaining important proteins like albumin in the bloodstream. When the kidneys are damaged, their filtering membranes become leaky, allowing albumin to spill into the urine — a condition called albuminuria or proteinuria. Even small elevations in urinary albumin (microalbuminuria) are an early warning sign of kidney disease, often detectable years before kidney function visibly declines. The ACR is a critical screening tool for chronic kidney disease (CKD), diabetic nephropathy, and hypertensive kidney damage, and it also independently predicts cardiovascular disease risk, making it one of the most clinically important routine urine tests available.
Normal Ranges
Males
Less than 17 mg/g creatinine (optimal: <10 mg/g)
Females
Less than 25 mg/g creatinine (optimal: <10 mg/g)
Children
Less than 30 mg/g creatinine; varies by age and sex
Causes of High Levels
- Diabetic nephropathy — high blood sugar damages the kidney's filtering units (glomeruli), causing protein leakage
- Hypertension — chronically elevated blood pressure damages kidney blood vessels, impairing filtration
- Chronic kidney disease (CKD) — any progressive kidney damage increases albumin leakage into urine
- Urinary tract infection (UTI) — inflammation temporarily elevates urinary albumin levels
- Strenuous exercise or fever — transient increases in ACR can occur after intense physical activity or illness
- Heart failure — reduced cardiac output impairs kidney perfusion, increasing albumin excretion
- Obesity and metabolic syndrome — excess visceral fat promotes systemic inflammation and kidney stress
Causes of Low Levels
- Well-controlled diabetes — effective blood sugar management protects kidney filtering function
How to Improve Your Albumin-Creatinine Ratio
Diet
- Reduce sodium intake to less than 2,300 mg per day to lower blood pressure and decrease kidney filtration stress
- Limit processed and red meat consumption; consider moderate plant-based protein sources like legumes and tofu to reduce kidney workload
- Follow a low-glycemic diet rich in vegetables, whole grains, and fiber to improve blood sugar control and reduce diabetic kidney injury
- Increase omega-3 fatty acid intake from fatty fish (salmon, mackerel) or flaxseed to reduce kidney inflammation
- Avoid high-fructose corn syrup and sugar-sweetened beverages, which worsen insulin resistance and blood pressure
Supplements
- Omega-3 fatty acids (EPA+DHA): 2,000–4,000 mg/day may reduce urinary albumin in diabetic kidney disease
- Vitamin D3: 1,000–2,000 IU/day — deficiency is associated with higher ACR and CKD progression
- Coenzyme Q10 (CoQ10): 100–300 mg/day may improve kidney cell energy metabolism and reduce oxidative stress
- Magnesium glycinate: 200–400 mg/day supports blood pressure regulation and glucose metabolism
- Alpha-lipoic acid: 300–600 mg/day has antioxidant properties that may protect kidney cells in diabetic nephropathy
Related Biomarkers
Frequently Asked Questions
What is a dangerously high ACR level?
ACR levels are categorized into three stages: normal (less than 30 mg/g), moderately increased or microalbuminuria (30–300 mg/g), and severely increased or macroalbuminuria (greater than 300 mg/g). An ACR above 300 mg/g indicates significant kidney damage and requires prompt medical evaluation and treatment. Values above 2,000–3,000 mg/g are seen in nephrotic syndrome, a serious condition where the kidneys lose large amounts of protein.
Do I need to fast before an ACR urine test?
No fasting is required for a urine ACR test. However, you should avoid vigorous exercise for at least 24–48 hours before the test, as strenuous activity can temporarily raise urinary albumin levels and produce a falsely elevated result. Testing during a urinary tract infection should also be postponed if possible, as infection inflames the urinary tract and can transiently increase albumin in urine.
Can a high ACR be reversed or improved?
Yes, especially in the early stages. Microalbuminuria (ACR 30–300 mg/g) is often reversible or significantly reducible with the right interventions. Controlling blood pressure (particularly using ACE inhibitors or ARBs), tightly managing blood sugar in diabetics, losing weight, quitting smoking, and reducing sodium intake have all been shown to lower ACR. Some patients can normalize their ACR entirely with lifestyle changes and medication, though this depends on the underlying cause and severity of kidney damage.
How often should I get an ACR test?
Testing frequency depends on your risk profile. People with diabetes (type 1 or type 2) should be screened annually once they have had the disease for five years (type 1) or at diagnosis (type 2). People with high blood pressure, a family history of kidney disease, or obesity should be screened at least every 1–2 years. If you already have elevated ACR or CKD, your doctor may recommend testing every 3–6 months to monitor disease progression or treatment response.