A 66-year-old woman on maintenance hemodialysis presents with dyspnea. Cardiac troponin T is mildly elevated at 0.09 ng/mL (upper reference limit 0.01), while troponin I is within normal limits. Echocardiography shows no regional wall motion abnormality. The BEST explanation for the troponin T result is:
- A Troponin T is cleared exclusively by the kidney, unlike troponin I
- B Chronic low-grade myocardial injury and increased troponin T expression in failing myocardium commonly cause baseline elevation in end-stage renal disease ✓
- C Skeletal muscle regeneration releases troponin T into the circulation
- D Hemodialysis membranes adsorb troponin I, spuriously lowering its value
Correct answer: B. Chronic low-grade myocardial injury and increased troponin T expression in failing myocardium commonly cause baseline elevation in end-stage renal disease
Explanation
Many patients with end-stage renal disease have chronically elevated troponin T, often with normal troponin I, reflecting left ventricular hypertrophy, microinfarcts, and re-expression of the fetal troponin T isoform in remodeled myocardium rather than assay interference or renal retention alone. This matters clinically: in dialysis patients, a stable baseline troponin T does not diagnose acute coronary syndrome, whereas a rising trend above the individual baseline does. Skeletal muscle does not release cardiac troponin T.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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