Normalization of creatine kinase level during pregnancy in idiopathic hyperCKemia

A 34-year-old previously healthy woman with no remarkable family history developed asymptomatic hyperCKemia at age 26. Over the next 6 years, hyperCKemia persisted (502-2562 IU/l; normal range<180). A muscle biopsy showed minimal nonspecific myopathy. Genetic analysis of blood and muscle samples showed no abnormality in the dystrophin gene. At age 33, she became pregnant for the first time and serum creatine kinase (CK) was normal at 170 IU/l in the third trimester. After delivery, hyperCKemia reappeared (715-2620) while her baby tested normal for CK. This is the first report of idiopathic hyperCKemia associated normalization of serum CK level during pregnancy, which has been reported in carriers of Duchenne muscular dystrophy.