Albumin/creatinine ratio

Albumin/Creatinine Ratio (ACR) is a medical diagnostic test used to assess the presence and degree of proteinuria (the presence of albumin in the urine). This test is significant in the detection and management of kidney disease, particularly in individuals with risk factors such as diabetes, hypertension, and cardiovascular disease. The ACR is calculated by dividing the albumin concentration in the urine by the creatinine concentration. This ratio provides a more accurate assessment of kidney function than measuring albumin or creatinine levels alone.

Overview

Albumin is a type of protein that is normally found in the blood. Its presence in the urine is an early indicator of kidney damage, as healthy kidneys do not usually allow a significant amount of albumin to pass into the urine. Creatinine, a waste product of muscle metabolism, is filtered out of the blood by the kidneys. Measuring the ratio of albumin to creatinine in the urine helps to normalize the albumin level, accounting for variations in urine concentration.

Indications

The ACR test is recommended for individuals at risk of developing kidney disease, including those with:

• Diabetes
• Hypertension
• Family history of kidney disease
• Previous diagnosis of kidney disease

It is also used to monitor the progression of kidney disease and the effectiveness of treatment in individuals already diagnosed with the condition.

Interpretation

The results of the ACR test are usually reported in milligrams of albumin per gram of creatinine (mg/g). The following ranges are used to interpret the results:

• Normal: Less than 30 mg/g
• Microalbuminuria: 30 to 300 mg/g
• Macroalbuminuria: Greater than 300 mg/g

Microalbuminuria indicates early-stage kidney disease, while macroalbuminuria suggests more advanced kidney damage.

Clinical Significance

Early detection of kidney damage through the ACR test allows for timely intervention, which can slow the progression of kidney disease and reduce the risk of complications, such as cardiovascular disease and end-stage renal disease. Management strategies may include controlling blood sugar levels in diabetics, managing blood pressure, making dietary changes, and using medications that protect kidney function.

Limitations

While the ACR test is a valuable tool for assessing kidney health, it has some limitations. Dehydration, exercise, and certain medications can affect the results. Additionally, a single test may not be sufficient for diagnosis, and multiple tests over time may be necessary to confirm the presence of kidney disease.