Digoxin-like immunoreactive substance in postmortem blood of infants and children.

A digoxin-like immunoreactive substance (DLIS) has been reported in the serum of infants not receiving digoxin. This study was undertaken to determine if DLIS is present in the postmortem blood and tissues of infants or children and whether the endogenous substance could interfere with forensic toxicological analysis in suspected overdose. Ninety blood specimens taken from the heart at autopsy of children or infants were screened for DLIS using commercial radioimmunoassay kits. The average age at death in these cases was 8.6 months, the median age was 2 months. DLIS equivalent to 0.25 to 2.0 ng/mL digoxin was found in one third of the cases. The incidence of positive findings was 5/6 stillborns, 10/45 Sudden Infant Death Syndrome (SIDS), 10/15 deaths as a result of infection, 4/7 homicides, 1/8 deaths caused by congenital defects, and 0/9 accidental deaths. The body distribution of DLIS was investigated and highest levels were found in the liver. Findings of DLIS in blood were correlated with renal failure, (elevated vitreous urea nitrogen), electrolyte imbalance, and liver trauma. Apparent concentrations were in the equivalent therapeutic range of digoxin and would not be confused with accidental or intentional overdose with digoxin.