What is a normal microalbumin (Microalbumin)/creatinine ratio in a urine panel?

From the Guidelines

A normal microalbumin/creatinine ratio (UACR) is less than 30 mg/g. This test measures the amount of albumin (a protein) in your urine compared to creatinine, providing an assessment of kidney function. Values between 30-300 mg/g indicate microalbuminuria, suggesting early kidney damage, while values above 300 mg/g indicate macroalbuminuria, signifying more significant kidney damage.

Key Points to Consider

• The test is particularly important for monitoring kidney health in patients with diabetes, hypertension, or other conditions that put kidneys at risk, as stated in 1.
• For accurate results, a random spot urine sample is typically sufficient, though first-morning samples may be preferred for consistency, as noted in 1.
• The test should be performed annually for at-risk patients, such as those with diabetes or hypertension, according to 1.
• Elevated results should be confirmed with repeat testing, as transient increases can occur due to factors like fever, exercise, urinary tract infections, or heart failure, as mentioned in 1.
• Maintaining good blood pressure and blood glucose control can help prevent kidney damage and keep this ratio in the normal range.

Important Considerations for Interpretation

• High biological variability of >20% between measurements in urinary albumin excretion means that two of three specimens of UACR collected within a 3- to 6-month period should be abnormal before considering a patient to have high or very high albuminuria, as stated in 1.
• Factors such as exercise within 24 h, infection, fever, congestive heart failure, marked hyperglycemia, menstruation, and marked hypertension may elevate UACR independently of kidney damage, as noted in 1.

Recommendations for Monitoring and Management

• An eGFR persistently <60 mL/min/1.73 m2 in concert with a urine albumin value of >30 mg/g creatinine is considered abnormal, though optimal, as stated in 1.
• Prompt referral to a nephrologist is recommended for uncertainty about the etiology of kidney disease, difficult management issues, and rapidly progressing kidney disease, according to 1.

From the Research

Normal Microalbumin/Creatinine Ratio Panel

• The normal microalbumin/creatinine ratio is less than 30 mg/g 2, 3
• Microalbuminuria is defined as a urinary albumin-to-creatinine ratio of 30 to 300 mg/g 2
• Macroalbuminuria is defined as a urinary albumin-to-creatinine ratio of more than 300 mg/g 2

Diagnosis and Screening

• Microalbuminuria screening is mandatory in individuals at risk of developing or presenting elevated global CV risk 2
• Routine annual screening can detect changes in urine albumin excretion and improve the timely identification of albuminuria 4
• Preferred simple screening methods include microalbumin-specific dipsticks and urinary albumin:creatinine ratio determination (from a spot urine sample) 4

Treatment and Management

• Intensive treatment with the administration of an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker can diminish the risk accompanying albuminuria in hypertensive patients with or without CKD and diabetes 2
• Cornerstones of albuminuria treatment include risk factor management, ongoing monitoring, and the use of renin-angiotensin-aldosterone system (RAAS)-blocking agents 4
• The combined use of an ACE inhibitor and ARB was once considered a viable option for the treatment of albuminuria, but results of the Ongoing Telmisartan Alone and in Combination With Ramipril Global Endpoint Trial (ONTARGET) raised important questions regarding the benefits and limitations of dual RAAS blockade 4

Prognosis and Outcomes

• Low levels of albuminuria, UACR below 30 mg/g, are associated with increased risk of incident hypertension and CVD mortality at follow-up, but are not associated with increased risk of incident diabetes mellitus 3
• The prevalence of albuminuria ≥300 mg/g was 2.8% in 2001 to 2006,2.8% in 2007 to 2012, and 3.2% in 2013 to 2018 5
• ACE inhibitor/ARB underutilization represents a significant gap in preventive care delivery for adults with hypertension and albuminuria that has not substantially changed over time 5