Direct-to-consumer cardiac screening tests: user beware.

Normal insulin with undetectable C-peptide concentrations indicates exogenous insulin administration in a bodybuilder (1 ). Insulin has anabolic functions that inhibit breakdown and promote nutrient storage (2 ). Pharmaceutical-grade insulin is available without prescription, providing an easy-to-obtain performance enhancer (3). Although a urinary testosterone/ luteinizing hormone ratio 30 is a diagnostically sensitive marker for anabolic steroids (4 ), the combination of increased testosterone and undetectable luteinizing hormone in plasma suggests exogenous use. The prevalence of doping in recreational athletes is estimated at up to 15% (5 ), making this scenario possible in many hospitals.