Statin-associated myopathy with normal creatine kinase levels. Case report from a Norwegian family.

Trøseid M, Henriksen OA, Lindal S. Statin-associated myopathy with normal creatine kinase levels - case report from a Norwegian family. APMIS 2005;113:635-7. Recent reports suggest that statins may cause myopathy with normal creatine kinase levels. We describe four related patients with statin-associated muscle symptoms and normal creatine kinase levels. In two out of the four patients (mother and son), pathological findings on EMG suggested myopathy, and muscle biopsies showed evidence of mitochondrial pathology. A third patient (daughter) had slight myopathic findings on EMG and muscle biopsy, but not enough to be classified as pathological. In a fourth patient, there were no pathological findings. Creatine kinase levels were normal and symptoms diminished after discontinuation of drugs in all four patients. Our findings are consistent with other reports of statin-associated myopathy with normal creatine kinase levels. An inherited vulnerability, possibly a mitochondrial pathology, might cause or aggravate symptoms in some patients.