RESUMEN
BACKGROUND: Preeclampsia is a frequent cause of maternal or fetal morbidity and mortality. There have been many trials to use microalbuminuria as a predictor for preeclampsia, but the usefulness is controversial. Authors have studied the changes in urinary microalbumin excretion during normal pregnancy to help establish a reference interval in which physiologic alteration during pregnancy is reflected. METHODS: During the period from January to April 1999 and from December 1999 to January 2000, urinary albumin and creatinine levels were measured in the 151 spot urine samples from pregnant women visiting Hanyang University Kuri Hospital for prenatal care. They were free of hypertension, proteinuria, and renal diseases at the time of sampling for the medical records. A homemade ELISA and the Cobas Integra 700 were used to measure the urinary albumin and urinary creatinine levels. The analysis of the data was performed as urinary microalbumin/creatinine ratio (ACR). RESULTS: In the 146 urine samples from normotensive pregnant women, urine ACR was 1.36+/-1.72 g/mol (mean+/-standard deviation). The urine ACR was 0.83+/-1.12 g/mol in the first trimester, 1.06+/-1.38 g/mol in the second trimester, and 1.82+/-1.06 g/mol in the third trimester. The urine ACR of the third trimester was significantly different from that of the first or second trimester (3rd vs 1st, P=0.026 and 3rd vs 2nd, P=0.011). CONCLUSIONS: During the course of normal pregnancy, urinary microalbumin excretions increased significantly in the third trimester. It is necessary that the reference interval for urinary microalbumin excretions be established based on gestational weeks.