The contribution of steroids to digoxin-like immunoreactivity in cord blood.
Samples of cord serum from 29 healthy neonates were analysed for digoxin-like immunoreactive substance (DLIS), cortisol, 17 beta-oestradiol, progesterone, dehydroepiandrosterone-sulphate (DHEAS), 17 alpha-hydroxyprogesterone (17OHP), androstenedione, oestriol and ouabain-like activity (OLA; by inhibition of Na+, K+ATPase activity). The mean serum concentration of DLIS was 0.91 (SD = 0.19) nmol/L and the mean OLA was 26.1 (SD = 11.5) nmol/L. There was no correlation between DLIS and OLA. DLIS correlated significantly with oestriol (r = 0.521), progesterone (r = 0.534) and 17OHP (r = 0.43). Stepwise multiple regression analysis showed that 17 beta-oestradiol, progesterone and androstenedione contributed to DLIS and the intercept was 0.64 (SD = 0.127). The concentrations of steroids (17 beta-oestradiol, progesterone, androstenedione) required to displace digoxin by 50% in the digoxin immunoassay and inhibit Na+,K+ATPase in the OLA assay were 10(3)-10(4)-fold higher than those found in cord serum. We conclude that the contribution of these steroids to DLIS is small and that DLIS and OLA measure different compounds.
Yun
W S
WS
Prenatal Diagnostic Laboratory, Tsan Yuk Hospital, Hong Kong.
Ho
C S
CS
Panesar
N S
NS
Swaminathan
R
R
D003429:Cross Reactions; D004077:Digoxin / Q000276:immunology*; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013256:Steroids / Q000097:blood*
D013256:Steroids; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase