For many people, albuminuria is the earliest sign of CKD. A urine albumin-to-creatinine ratio (UACR) on a spot urine specimen is the recommended test to assess and monitor urine albumin.
UACR is a ratio between two measured substances.
Urine Albumin (mg/dL) = UACR in mg/g ≈ Albumin excretion in mg/day
Urine Creatinine (g/dL)
Urine albumin is a continuous risk factor. UACR greater than 30 mg/g is considered abnormal. Traditionally, 30–300 mg/g has been called microalbuminuria and greater than 300 mg/g has been called macroalbuminuria. However, the 300 mg/g cut-off merely represents a rough correlation with the lower limit of sensitivity of the traditional urine dipstick for albumin. Thus, the albuminuria cut-offs are derived from laboratory methods rather than clinically relevant endpoints.
Stable or lower levels of albuminuria may indicate therapy is effective. Increasing or elevated levels may indicate progression of CKD.
The NKDEP Laboratory Working Group, in collaboration with the International Federation of Clinical Chemistry and Laboratory Medicine, has undertaken an effort to standardize the laboratory assessment of urine albumin and the reporting of results to clinicians.
Page last updated: March 1, 2012