Albumin-to-Creatinine Ratio (ACR)

The albumin-to-creatinine ratio (ACR) is a medical test used to diagnose and monitor kidney disease, particularly diabetic nephropathy and other conditions that affect the kidneys' ability to filter waste products from the blood.

What is the ACR test?

The ACR test measures the amount of albumin (a type of protein) in a patient's urine compared to the amount of creatinine (a waste product). The test is usually performed on a random urine sample, and the results are expressed as a ratio of milligrams of albumin per gram of creatinine (mg/g).

How is the ACR test used?

The ACR test is used to:

• Detect early signs of kidney damage or disease, particularly in patients with diabetes or hypertension
• Monitor the progression of kidney disease and adjust treatment plans accordingly
• Assess the effectiveness of treatments aimed at reducing proteinuria (excess protein in the urine)

Interpretation of ACR results

The interpretation of ACR results varies depending on the laboratory and the specific testing method used. However, general guidelines are as follows:

• Normal: Less than 30 mg/g (or less than 3.4 mg/mmol)
• Mildly increased: 30-300 mg/g (or 3.4-34 mg/mmol)
• Moderately increased: 300-1000 mg/g (or 34-110 mg/mmol)
• Severely increased: Greater than 1000 mg/g (or greater than 110 mg/mmol)

Limitations and considerations

The ACR test has some limitations, including:

• Variability in urine concentration, which can affect the accuracy of the results
• Pregnancy or menstrual cycle, which can increase albumin levels in the urine
• Recent exercise or physical activity, which can also increase albumin levels
• Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), which can affect kidney function and albumin excretion

Conclusion

The albumin-to-creatinine ratio is a valuable tool for diagnosing and monitoring kidney disease. By measuring the amount of albumin in the urine compared to creatinine, healthcare providers can assess kidney function and detect early signs of damage or disease.