Troponin I levels in a hemolytic uremic syndrome patient with severe cardiac failure

Troponins are highly sensitive and specific biochemical markers of myocardial injury that are released into the circulation during myocardial ischemia. We describe changes in cardiac troponin I (cTnI) prior to and following clinical evidence of severe myocardial dysfunction in a child with hemolytic uremic syndrome (HUS). A previously healthy, 22-month-old girl presented with typical HUS and stool cultures positive for Escherichia coli O157:H7. She required dialysis, blood and platelet transfusions, and insulin for HUS-related diabetes mellitus. On the 6th hospital day she had sudden circulatory collapse with a blood pressure of 70/40 mmHg and an oxygen saturation of 88%. She responded rapidly to emergency resuscitation but had diminished left ventricular function (ejection fraction 18%). Four days after the acute event an echocardiogram showed normal ventricular size and contractility. She underwent hemodialysis for 22 days, and renal function was normal after 33 days. cTnI levels were measured with a microparticle enzyme immunoassay. cTnI was normal (>0.4 mug/l) 32 h prior to cardiac collapse, mildly increased (2.1 mug/l) 8 h before the cardiac collapse, severely elevated shortly after the cardiac event (43.1 mug/l), and peaked (140.6 mug/l) at 24 h. It then fell gradually and was normal at discharge. These results suggest that measurement of cTnI may be a useful predictor of cardiac involvement in severely affected children with HUS.