[Maternal concentration of serum digoxin and concentration in the amniotic fluid and neonatal serum].

Digoxin was assayed in maternal and neonatal sera and in the amniotic fluid in 14 pregnant patients chronically digitalized for mitral stenosis. Neonatal serum levels of digoxin are linearly correlated with maternal concentrations of the drug, and all are inversely related to maternal creatinine clearance. Amniotic fluid levels of the drug are not related to serum levels, but relate to amniotic fluid creatinine concentration. Fetal serum levels are identical to maternal ones for all practical purposes, but bear no relation to amniotic digoxin concentration. Digoxin was assayed with a commercial kit showing very little cross-reactivity with endogenous digoxin-like cross-reacting compounds. Pitfalls in commercial digoxin assays and clinical implications are discussed.