Low molecular mass proteins and urinary enzymes in amniotic fluid of healthy pregnant women at progressive stages of gestation.
OBJECTIVE
Amniotic fluid alpha1-microglobulin (alpha1-m) and beta2-microglobulin (beta2-m) levels, as well as N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities, were measured in the course of uncomplicated pregnancies to assess their variations as gestation progresses.


METHODS
Samples were obtained from 141 healthy pregnant women divided into three groups on the basis of gestational stage. Quantitative estimation of proteins was performed immunometrically and enzyme activities were determined spectrophotometrically.


RESULTS
It was found that, during pregnancy, alpha1-m and beta2-m concentrations as well as AAP activity significantly decrease, although their reduction patterns vary. Controversial results were found for NAG activity: the normalization of values for amniotic fluid creatinine significantly changed the reduction pattern of this enzyme. No statistically significant differences were found between male and female fetuses for amniotic fluid values of the biochemical substances studied.


CONCLUSIONS
The behavior observed for alpha1-m, beta2-m, and AAP might be linked to the progressive development and maturation of fetal renal tubular function. Amniotic fluid total NAG activity seems not to depend only on fetal urinary excretion.
Mussap
M
M
Department of Laboratory Medicine, School of Medicine, University of Padova, Italy.
Fanos
V
V
Piccoli
A
A
Zaninotto
M
M
Padovani
E M
EM
Plebani
M
M
D000118:Acetylglucosaminidase / Q000032:analysis*; D000510:Alpha-Globulins / Q000032:analysis; D000653:Amniotic Fluid / Q000737:chemistry*; D000704:Analysis of Variance; D018826:CD13 Antigens / Q000032:analysis*; D005260:Female; D005333:Fetus / Q000378:metabolism; D005865:Gestational Age; D006801:Humans; D007668:Kidney / Q000196:embryology; D016014:Linear Models; D008970:Molecular Weight; D011247:Pregnancy; D012712:Serum Globulins / Q000032:analysis*; D001613:beta 2-Microglobulin / Q000032:analysis
D000510:Alpha-Globulins; D012712:Serum Globulins; C016001:alpha-1-microglobulin; D001613:beta 2-Microglobulin; D000118:Acetylglucosaminidase; D018826:CD13 Antigens