Serum digoxin-like immunoreactive factor in children and its relation to sodium metabolism.
Serum digoxin-like immunoreactive factor (DLIF), an endogenous substance that cross-reacts with antidigoxin antibodies, was assessed (fluorescence polarization immunoassay) in children (n = 134) aged 5-16 y, who had never been treated with cardiac glycosides. DLIF was found in 50% of serum samples at a mean concentration of 0.16 +/- 0.06 ng/ml (range 0.03-0.35 ng/ml). Although the study population as a whole was apparently homogeneous with regard to serum sodium content, and none had clinical signs of sodium imbalance, children with DLIF showed significantly lower natraemia (p = 0.0002), higher urinary concentration (p = 0.001) and fractional excretion (p = 0.001) of sodium, and increased systolic blood pressure (p = 0.009) compared with children without DLIF. Inverse correlations were found between DLIF concentration and serum sodium (p < 0.01), urine sodium content (p < 0.001), 24-h sodium excretion (p < 0.001), systolic (p < 0.001) and diastolic (p < 0.01) blood pressure. These findings suggest that sodium handling is different in children with and without DLIF, since this material seems to be released preferably in subjects who show a trend towards negative sodium balance. Such an association suggests that DLIF may be a physiologically relevant material involved in sodium homeostasis.
Garbagnati
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E
Paediatric Department IV, University of Milan, L. Sacco Hospital, Italy.
D000293:Adolescent; D002298:Cardenolides; D002648:Child; D002675:Child, Preschool; D004077:Digoxin; D005260:Female; D006706:Homeostasis; D006801:Humans; D008297:Male; D012503:Saponins / Q000097:blood*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D018709:Statistics, Nonparametric
D002298:Cardenolides; D012503:Saponins; C034504:digoxin-like factors; D004077:Digoxin; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase