Digoxin-like immunoreactive substance in pregnancy

Abstract

Our aims were to determine the potential usefulness of digoxin-like immunoreactive substances in the prediction of preeclampsia, to study the relationship between fetal production of these substances and maternal serum levels, and to evaluate the association between digoxin-like immunoreactive substances and plasma volume findings in preeclamptic pregnancies. Serum digoxin-like immunoreactive substance concentrations were measured in normotensive and preeclamptic pregnant women and in umbilical artery and vein blood samples. None of the patients in the first trimester (n = 53) and 11% of those in the second (n = 56) had detectable levels of this substance. However, 91% of the patients in the third trimester (n = 161) had positive results. The concentrations of digoxin-like immunoreactive substances in the preeclamptic group (n = 78) were significantly (p less than 0.005) lower than those of third-trimester (n = 83) normotensive patients (0.22 +/- 0.12 versus 0.32 +/- 0.15 ng/ml). However, there were no significant differences between the two groups regarding digoxin-like immunoreactive substance concentrations when matched for gestational age (41 patients in each group). Digoxin-like immunoreactive substance concentrations in umbilical vessels were significantly higher (p less than 0.001) than the corresponding maternal levels. Umbilical vessel digoxin-like immunoreactive substance levels demonstrated good correlation with fetal gestational age and birth weight in both normotensive and preeclamptic pregnancies. On the other hand, there was a poor (r = 0.02; p = 0.91) correlation between plasma volume findings and digoxin-like immunoreactive substance concentration. We conclude that the digoxin-like immunoreactive substance level may be of very little value in the prediction of preeclampsia. The presence of digoxin-like immunoreactive substance at greater concentrations in the umbilical cord blood samples suggests the possibility of the fetus as the source of this substance. Digoxin-like immunoreactive substances may not play a major role in plasma volume expansion during pregnancy.