Purpose of Review: Neurologists commonly receive consultation requests regarding the evaluation of patients with an elevated serum creatine kinase (CK), a condition known as hyperCKemia. This article outlines an approach to the history and examination of patients with hyperCKemia in order to narrow the localization and differential of an elevated CK and guide possible next steps. This article aims to help clinicians identify treatable or reversible etiologies as well as those that will change management.
Recent Findings: An unrevealing patient history (assessing for acquired and hereditary etiologies) in an otherwise neurologically intact individual who has a normal nerve conduction study and EMG predicts that the likelihood of diagnosing the patient after further investigations will be quite low. After a comprehensive workup, a positive diagnosis is made in approximately 25% of cases of hyperCKemia.
Summary: The best predictors for added diagnostic yield with further testing in hyperCKemia are a higher level of CK and a younger age; the presence of weakness increases the likelihood of a specific cause other than idiopathic or familial hyperCKemia. Many etiologies do not yet have treatments that alter clinical outcomes, and, even in the absence of a specific diagnosis, good communication with patients and primary care providers remains essential to ensure longitudinal surveillance with expectant management for potential consequences. Many patients with hyperCKemia of uncertain etiology, however, will not develop significant muscle disease on longitudinal follow-up.