From the Guidelines
The normal microalbumin to creatinine ratio is less than 30 mg/g.
Definition of Normal Microalbumin to Creatinine Ratio
- The ratio is calculated by measuring the amount of albumin (a protein) in a urine sample and dividing it by the amount of creatinine (a waste product) in the same sample.
- A ratio of less than 30 mg/g is considered normal, while a ratio of 30-299 mg/g is considered microalbuminuria, and a ratio of 300 mg/g or higher is considered macroalbuminuria 1.
Methods of Measurement
- The microalbumin to creatinine ratio can be measured using a random spot urine collection, a 24-hour urine collection, or a timed urine collection 1.
- The spot urine collection is the preferred method because it is easy to perform and provides accurate results 1.
Clinical Significance
- Microalbuminuria is a marker of early kidney damage and is associated with an increased risk of cardiovascular disease and kidney disease progression 1.
- The microalbumin to creatinine ratio is used to diagnose and monitor kidney disease, particularly in patients with diabetes 1.
- It is recommended to perform annual screening for microalbuminuria in patients with diabetes, and to use the microalbumin to creatinine ratio as a marker of kidney disease progression and cardiovascular risk 1.
From the Research
Normal Microalbumin to Creatinine Ratio
The normal microalbumin to creatinine ratio is typically considered to be below 30 mg/g, as stated in the studies 2, 3, 4, 5, 6.
Key Findings
- A value above 0.03 mg/mg suggests that albumin excretion is above 30 mg/day and therefore microalbuminuria is present 2.
- Microalbuminuria is defined as a persistent elevation of albumin in the urine of >30 to <300 mg/d (>20 to <200 microg/min) 3.
- Low levels of albuminuria, UACR below 30 mg/g, are associated with increased risk of incident hypertension and CVD mortality at follow-up 4.
- Elevated UACR within normal range was associated with higher all-cause and cardiovascular mortality risk across almost all subgroups including participants without comorbidities 5.
- Microalbuminuria, defined as urinary albumin excretion >4.8 microg/min (corresponding to approximately 6.4 microg/min during daytime), is a strong and independent determinant of coronary heart disease and death 6.
Microalbuminuria Measurement
- Use of the morning spot urine test for albumin-to-creatinine measurement (mg/g) is recommended as the preferred screening strategy for all patients with diabetes and with the metabolic syndrome and hypertension 3.
- Microalbuminuria should be assessed annually in all patients and every 6 months within the first year of treatment to monitor the impact of antihypertensive therapy 3.