Elevated troponin levels in rhabdomyolysis as a predictor of mortality in patients with normal kidney and cardiac function

Objectives: Rhabdomyolysis is characterized by muscle breakdown and the release of myocyte contents into the bloodstream, which can lead to severe complications. Elevated troponin levels, typically a marker of heart muscle injury, have been observed in rhabdomyolysis, but their clinical significance in this context remains unclear. This study aimed to evaluate the association between elevated troponin levels and mortality in patients with rhabdomyolysis, specifically those with normal kidney function and left ventricular function. Methods: This single-centre, retrospective study was conducted at a tertiary university medical centre from 2010 to 2022. The study included 252 patients diagnosed with rhabdomyolysis, defined by a creatine phosphokinase (CPK) level at least five times the upper normal limit. Patients were stratified into troponin-positive and troponin-negative groups. Only patients with an estimated glomerular filtration rate (eGFR) above 90 ml/min and normal left ventricular function were included. The primary outcome was 90-day survival, with secondary outcomes including 30-day survival and in-hospital mortality. Results: Patients with elevated troponin levels had significantly higher 90-day mortality rates, longer hospital stays, and were older with more comorbidities compared to the troponin-negative group. These patients had worse outcomes despite lower CPK levels in the troponin-positive group. The receiver operating characteristic (ROC) analysis showed a limited predictive value for CPK levels for troponin positivity. Conclusions: Elevated troponin levels in rhabdomyolysis, particularly in older patients, are associated with increased mortality, independent of kidney and left ventricular function. This suggests the need for heightened monitoring and potentially more aggressive management of these patients.