Categories for albuminuria and proteinuria

Normal urine contains small amounts of albumin, low-molecular-weight serum proteins, and proteins derived from renal tubules and the lower urinary tract. Albuminuria and proteinuria can be measured using excretion rates in timed urine collections, ratio of concentrations to creatinine concentration in spot urine samples, and semiquantitative dipsticks in spot urine samples. Relationships among measurement methods within a category are not exact.
Normal albumin and protein excretion rates are <10 and <50 mg/day, respectively. In most kidney diseases, albumin is the predominant urine protein, comprising approximately 60 to 90 percent of urine protein when protein excretion rate is very high. Urine albumin excretion rate of 30 to 300 and >300 mg/day correspond to moderately increased albuminuria (formerly "microalbuminuria") and severely increased albuminuria (formerly "macroalbuminuria"), respectively. Urine albumin and protein excretion rates of >2200 and >3500 mg/day are usually accompanied by signs and symptoms of nephrotic syndrome (hypoalbuminemia, hypercholesterolemia, and edema).
Albuminuria and proteinuria may be assessed from ACR and PCR. ACR and PCR are best determined by repeated measurement in morning first voided urine. In general, for clinical decision-making, ACR and PCR are sufficient, but AER and PER can be measured as a confirmatory test. Relationships between AER and ACR and between PER and PCR are based on the assumption that average creatinine excretion rate is 1 g/day. Creatinine excretion varies with age, sex, race and diet; therefore, the relationship among these categories is approximate only. ACR <10 mg/g (<1.1 mg/mmol) is considered normal; ACR 10 to 29 mg/g (1.1 to 3.3 mg/mmol) is considered "mildly increased."
Proteinuria may be assessed from semiquantitative urine dipsticks. The relationship between urine dipstick results and other measures depends upon urine concentration. In particular, a "trace" result can correspond to the "normal to mildly increased" category or low range of the "moderately increased" category. Positive dipstick tests can be confirmed by ACR, PCR, AER, or PER.
For ACR and PCR, to convert from mg/g creatinine to mg/mmol of creatinine, multiply by 0.113.