FETAL URINARY BIOCHEMISTRY PREDICTS POSTNATAL RENAL-FUNCTION IN CHILDREN WITH BILATERAL OBSTRUCTIVE UROPATHIES

Objective: To investigate the ability of fetal urinalysis to predict i n utero the renal function of children with bilateral uropathy who sur vive to the second year of life. Methods: This was a prospective cohor t study of 100 consecutive patients with prenatal diagnosis of bilater al uropathy who underwent fetal urine sampling. Fetal urinary concentr ations of sodium, chloride, calcium, phosphorus, ammonium, urea, creat inine, glucose, proteins, and beta2 microglobulin were measured. Prena tal findings were matched with renal function of survivors at 1-2 year s. The single end point was serum creatinine, which was considered abn ormal when greater than 50 mumol/L (0.56 mg/dL) during the second year of life. Results: Elevated serum creatinine was found in 17 of 42 chi ldren with isolated uropathy who survived more than 1 year. For predic tion of elevated serum creatinine during the second year of life, the fetal urinary concentration of beta2 microglobulin was both specific ( 0.83) and sensitive (0.80); sodium, chloride, and urea levels were sen sitive (0.70 or greater) but lacked specificity (less than 0.65); and fetal urinary glucose, phosphorus, calcium, ammonium, and total protei ns were specific (0.70 or greater) but lacked sensitivity (0.65 or les s). Conclusions: Our results provide a new approach to prenatal manage ment of congenital obstructive uropathies by identifying those fetuses at risk for survival with suboptimal renal function. These fetuses mi ght benefit from intrauterine therapy. In contrast, no attempt at pren atal uro-amniotic shunting should be made when a spontaneously good ou tcome is predicted by fetal urinalysis.