Comparison of placental isoferritin levels in maternal serum and coelomic and amniotic fluids during first trimester human gestation.

Placental isoferritin (PLF) is present in serum at high concentrations throughout normal gestation. The current study compared PLF concentrations in first trimester maternal serum with those of amniotic and coelomic fluids in 25 healthy, pregnant women. Use of a specific enzyme-linked immunosorbent assay indicated concentrations high (22 +/- 3 U/ml) in maternal serum, whereas significantly lower values were detected in both coelomic and amniotic fluids (5 +/- 2 and 3 +/- 2 U/ml, respectively, P < 0.005). It was further demonstrated that when pure PLF was added to amniotic and coelomic fluids, the PLF levels remained low in each compartment, suggesting that bioproducts produced inside the gestational sac may interfere with the PLF immunoassay.