Fetal serum beta(2)-microglobulin predicts postnatal renal function in bilateral uropathies

Background. Predicting postnatal renal function is crucial for the prenatal evaluation of fetal bilateral uropathies. Prenatal ultrasound can identify intrauterine terminal renal failure, but is not sensitive enough to identi fy those infants who would survive with an impaired renal function. Because it reflects fetal glomerular filtration, fetal serum beta(2)-microglobulin is a potential predictor of postnatal renal function. Methods. Fetal serum beta(2)-microglobulin (beta(2)m) was assayed in 61 cas es of bilateral or low obstructive uropathy, 74 controls, and 17 cases of b ilateral renal agenesis, and was correlated with renal function. Results. Fetal serum beta(2)m was 3.2 mg/L (range 1.5 to 4.7) in controls ( N = 74), 9.5 mg/L (range 6.7 to 11.3) in bilateral renal agenesis (N = 17), 7 mg/L (5.1 to 10.6) in uropathy in which terminal renal failure resulted in termination of pregnancy (N = 26), and 3.7 mg/L (range 2.3 to 11.2) in l ive borns with uropathy (N = 35). In the latter subgroup, fetal serum beta( 2)m was significantly and positively correlated (r(2) = 0.91) with postnata l serum creatinine. All survivors with a postnatal serum creatinine less th an or equal to 50 mu mol/L had a fetal serum beta(2)m lower than 5 mg/L. Fo ur of 6 survivors With a postnatal serum creatinine > 50 mu mol/L had a fet al serum beta(2)m greater than 5 mg/L. Conclusion. Fetal serum beta(2)-microglobulin is a marker for renal functio n and predicts postnatal serum creatinine in bilateral or low fetal obstruc tive uropathy.