S4882 Persistent Asymptomatic Elevation of Creatine Phosphokinase in a Patient With Crohn’s Ileitis on Vedolizumab Therapy

Introduction: Gut-selective anti-integrin monoclonal antibodies, including vedolizumab, are effective therapies for managing severe cases of inflammatory bowel disease. Unlike tumor necrosis factor inhibitors, which have been associated with myopathic side effects, Vedolizumab targets the α4β7 integrin, inhibiting leukocyte migration into the gastrointestinal mucosa. One study has shown that over 30% of inflammatory bowel disease patients receiving infliximab therapy may develop asymptomatic elevations in serum creatine kinase as an adverse effect. However, data on vedolizumab-induced creatine kinase (CK) abnormalities remain limited. Case Description/Methods: A 36-year-old non-smoking man with a history of Crohn’s ileitis diagnosed at age 24 well-controlled on vedolizumab, was found to have persistently elevated CK levels, peaking at 3000 U/L, with subsequent values ranging from 1000 to 2437 U/L for 1 year. CK Isoenzymes revealed benign skeletal muscle source rather than inflammatory myopathy. He remained asymptomatic, denying myalgias, weakness, dark urine, or exercise intolerance. Neurological examination and electromyography were unremarkable. A muscle biopsy was offered but declined. Cardiac evaluation, including stress testing and echocardiography, was unrevealing. Autoimmune panel ANA, dsDNA, SSA/SSB, Smith, RNP, RF, and CCP all negative. Erythrocyte sedimentation rate and C-reactive protein were within normal limits. Normal thyroid function tests. He denied use of steroids, statins, creatine, supplements, or alcohol. Family history was negative for neuromuscular disease. CMP notable only for mild transaminitis (AST 74, ALT 69), with normal GGT, Uric acid and G6PD levels. Infectious workup including hepatitis B/C panel and QuantiFERON® testing was negative. Complete blood count was unremarkable and hepatic steatosis noted on imaging with normal renal function. Discussion: This case highlights that asymptomatic CK elevations, though not widely reported, may occur in some patients on biologic therapy. Studies have noted such elevations with tumor necrosis factor inhibitors like infliximab and, less frequently, with vedolizumab, though the mechanism is unclear. Clinicians should keep a broad differential and rule out other causes—such as statin use, thyroid dysfunction, or myopathies—before attributing elevated CK to biologic therapy. High serum creatine kinase levels in infliximab- and vedolizumab-treated inflammatory bowel disease patients.