To the Editor:
We appreciate the thoughtful comments by Papadimas et al. We agree on the potential benefit for obtaining a creatine kinase (CK) level in adults with an unknown etiology for elevated transaminases. Laboratory testing can never replace a thorough history and physical examination and should be used to augment thoughtful clinical judgment. A quick check of muscle strength and bulk can provide important information. Transaminase levels are a component of most standard metabolic laboratory panels and are frequently obtained in routine primary care and community screenings as well as a common first step in the workup of undifferentiated physical symptoms. A CK measurement is not part of most standard metabolic panels. Although not diagnostic of muscle disease, a CK and γ glutamyl transpeptidase measurement can help guide the clinical plan and follow-up for seeking and obtaining a definitive diagnosis. Too often, unnecessary gastrointestinal and invasive liver tests may be done on children and adults due to elevated transaminases. A CK measurement might help avoid these unnecessary tests and guide the clinical workup toward muscle disease. In the simplest scenario it might help the primary care clinician decide whether referral should be to a gastroenterologist (normal CK) or a neurologist (elevated CK). Early diagnosis of muscle disease can help prevent both acute and long-term sequelae of many muscle diseases. Adding a CK and γ glutamyl transpeptidase can help make an earlier diagnosis.
