The albumin-creatinine ratio is a urine test that helps evaluate how well the kidneys are working. It measures the amount of albumin, a type of protein, in relation to creatinine, a waste product that is filtered by the kidneys.
Under normal conditions, healthy kidneys keep most albumin in the blood. When the kidneys are damaged or under strain, small amounts of albumin can leak into the urine, which this test is designed to detect.
The albumin-creatinine ratio is widely used in the United States to screen for early kidney disease and to monitor people who are at higher risk, such as those with diabetes or high blood pressure.
What the test is used for
The albumin-creatinine ratio is used to detect early signs of kidney damage, often before symptoms appear. It is especially helpful for identifying chronic kidney disease in its early stages.
This test is commonly ordered for people with diabetes, high blood pressure, or a family history of kidney disease. It is also used to monitor kidney health over time and to assess the risk of kidney and cardiovascular complications.
How the test is performed
The test is performed using a urine sample, most often a single spot urine sample collected at any time of day. In some cases, a first-morning urine sample may be preferred because it is more concentrated.
In the laboratory, the amount of albumin and creatinine in the urine is measured, and the ratio between them is calculated. Using a ratio helps correct for differences in urine concentration between samples.
Normal values
Results for the albumin-creatinine ratio are usually reported in milligrams of albumin per gram of creatinine.
A normal result is generally less than 30 mg/g. This range is considered normal to mildly increased and suggests that the kidneys are filtering protein properly.
What a high result means
A high albumin-creatinine ratio means that more albumin is passing into the urine than expected. This finding is known as albuminuria and often indicates kidney damage.
Values between 30 and 300 mg/g are considered moderately increased and may be linked to early kidney disease. Results above 300 mg/g are considered severely increased and are more strongly associated with chronic kidney disease, diabetes-related kidney damage, high blood pressure, and increased cardiovascular risk.
Temporary increases can also occur due to factors such as intense physical activity, fever, urinary tract infections, or poorly controlled blood sugar or blood pressure.
What a low result means
A low albumin-creatinine ratio, typically below 30 mg/g, is considered normal. It indicates that little to no albumin is leaking into the urine and that kidney filtration is functioning well.
Low results usually do not indicate a health problem and do not require further evaluation unless other kidney-related findings are present.
How to prepare for testing
In most cases, no special preparation is needed before an albumin-creatinine ratio test. Fasting and dietary changes are not required.
However, certain situations can affect results. Strenuous exercise, fever, infections, menstruation, or recent illness may temporarily raise albumin levels in urine. When possible, testing is best done when these factors are not present to improve accuracy.
Why repeat testing may be needed
An elevated albumin-creatinine ratio is often confirmed with repeat testing. This helps determine whether the increase is persistent or temporary.
Persistent elevation over several months is more suggestive of chronic kidney disease and may lead to further evaluation or monitoring.