Normal values of urinary albumin and total protein excretion during pregnancy.

OBJECTIVE

Our purpose was to determine the normal 24-hour excretion values of urinary albumin and total protein in healthy pregnant women.

METHODS

We evaluated 270 healthy pregnant women < or = 35 years old without a history of diabetes, hypertension, pyelonephritis, preeclampsia, or renal or connective tissue disease. Adequacy of 24-hour collection was determined by creatinine excretion.

RESULTS

The mean protein excretion in 24 hours was 116.9 mg, upper 95% confidence limit 259.4 mg. The mean albumin excretion in 24 hours was 11.8 mg, upper 95% confidence limit 28.7 mg. Both protein and albumin excretion increased after 20 weeks of gestation. No patient had evidence of microalbuminuria, defined as urinary albumin excretion > 30 mg/L.

CONCLUSIONS

These data support 260 mg per 24 hours of urinary protein and 29 mg per 24 hours of albumin as the upper limit of normal in pregnancy. Albumin accounts for a small fraction of total urinary protein excretion.