Fetal serum β2-microglobulin predicts postnatal renal function in bilateral uropathies

Abstract

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 identify those infants who would survive with an impaired renal function. Because it reflects fetal glomerular filtration, fetal serum β2- microglobulin is a potential predictor of postnatal renal function. Methods: Fetal serum β2-microglobulin (β2m) was assayed in 61 cases of bilateral or low obstructive uropathy, 74 controls, and 17 cases of bilateral renal agenesis, and was correlated with renal function. Results: Fetal serum β2m 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 live borns with uropathy (N = 35). In the latter subgroup, fetal serum β2m was significantly and positively correlated (r2 = 0.91) with postnatal serum creatinine. All survivors with a postnatal serum creatinine ≤50 μmol/L had a fetal serum β2m lower than 5 mg/L. Four of 6 survivors with a postnatal serum creatinine >50 μmol/L had a fetal serum β2m greater than 5 mg/L. Conclusion: Fetal serum β2- microglobulin is a marker for renal function and predicts postnatal serum creatinine in bilateral or low fetal obstructive uropathy.