[Assessment of fetal kidney function by determining the microprotein levels (alpha-1 and beta-2 microglobulin) in...

Fetal renal function cannot be assessed with clearance methods. Fetal urea and creatinine serum levels correspond to maternal values, the fetus being hemodialyzed by his mother till birth. To predict glomerular filtration independently of maternal renal function, levels of alpha 1-microglobulin (MG) and beta 2MG and creatinine were routinely determined in cord blood of 375 newborns (GA 25.-42 weeks) in cord blood and in 154 cases in corresponding maternal blood samples. alpha 1MG was determined in a radial immunodiffusion method, beta 2MG by radioimmunoassay, creatinine enzymatically. The mean alpha 1MG concentration fell from 3.1 mg/dl in 25-31 weeks prematures to 2.3 mg/dl in 38-42 week group (p less than 0.005), beta 2MG concentration fell from 3.9 mg/l to a mean of 2.6 mg/l (p less than 0.0005), while in maternal blood, levels rose from 4.0 to 4.3 mg/dl (alpha 1MG) and from 1.7 to 1.8 mg/l (beta 2MG) (n.s.). Creatinine levels rose from 0.63 to 0.75 mg/dl in both fetal and maternal blood. Parallel to the rise in GFR, microprotein levels fall during intrauterine development, while maternal serum levels increase. There is no correlation between maternal and cord blood alpha 1MG or beta 2MG concentrations. This is distinct in cases with severe maternal or fetal renal insufficiency (n = 10). Thus microprotein determination in fetal serum can be used to detect severe renal function disturbances and to estimate glomerular filtration rate independently of maternal renal function.