Clinical significance of markedly elevated serum creatine kinase levels in patients with acne on isotretinoin.

Muscle-related complaints and high creatine kinase (CK) blood levels have been reported in 16-51% of patients with acne treated with isotretinoin. It has been suggested that this retinoid and exercise have a synergistic effect on muscle. The presence of marked hyperCKemia during the treatment raises concern about rhabdomyolysis. The objective of this report was to evaluate the incidence, course and clinical significance of severe hyperCKemia in isotretinoin therapy for acne. Out of 442 patients on isotretinoin, we reviewed 7 patients (1.58%) with CK values above 5,000 IU/l. Only two of them had myalgia. Physical activity or intramuscular injection prior to blood testing was reported in 6 patients. CK values returned to normal within 2 weeks and all subjects except 2, completed treatment. In conclusion, marked hyperCKemia with or without muscle-related complaints in isotretinoin-treated patients with acne is a benign phenomenon.