The influence of gestational age and preeclampsia on the presence and magnitude of serum endogenous digoxin-like immunoreactive substance(s).

Digoxin-like immunoreactive substance(s) has been measured in serum during pregnancy. Because of its presence in pregnancy, investigators have suggested that digoxin-like immunoreactive substance may play an etiologic role in the development of preeclampsia. The objectives of this study were to evaluate the relationship between maternal digoxin-like immunoreactive substance and gestational age and compare digoxin-like immunoreactive substance concentrations in patients with and without preeclampsia who were in the third trimester. Two hundred twenty patients were studied during either the first (n = 53), second (n = 56), or third (n = 111) trimester of pregnancy. Digoxin-like immunoreactive substance was undetectable in the serum of patients during the first trimester; however, 11% of second-trimester and 96% of third-trimester patients had measurable levels of serum digoxin-like immunoreactive substance (p less than 0.05). The mean +/- SEM concentration of digoxin-like immunoreactive substance in serum in third-trimester patients was 0.29 +/- 0.01 ng/ml (range 0 to 0.58 ng/ml). Gestational age at delivery was significantly lower in patients with preeclampsia than in those without preeclampsia (36.3 +/- 0.6 versus 38.8 +/- 0.4 weeks; p less than 0.001). In addition, there was no statistical difference in mean +/- SEM concentration of digoxin-like immunoreactive substance between 27 patients without preeclampsia (0.32 +/- 0.02 ng/ml) and 27 patients with preeclampsia (0.30 +/- 0.02 ng/ml; p = 0.47) matched for gestational age. We conclude that (1) digoxin-like immunoreactive substance appearance and increasing serum concentration during pregnancy are correlated with increasing gestational age and (2) there is no difference in digoxin-like immunoreactive substance values between patients with and without preeclampsia, which may exclude digoxin-like immunoreactive substance as a predictor of preeclampsia.