Decreased Neuromuscular Function in Crohn's Disease Patients Is Not Associated with Low Serum Vitamin D Levels

Neuromuscular fatigue is a common complaint in Crohn's disease (CD) patients. A correlation between serum vitamin D concentrations and neuromuscular function has been found in the elderly or non-ambulant populations. The aim of this study was to determine whether CD patients exhibit impaired neuromuscular function and if so, is there a link between vitamin D and neuromuscular function. Crohn's disease patients (n = 19) with at least one prior small bowel resection and matched controls (n = 19) underwent muscle strength and endurance testing, vitamin D, and nerve function analysis. Knee extension and flexion peak torque (Nm/kg) were greater in the control group than in the CD patients (P = 0.04 and 0.014, respectively. A significant difference was found between fatigue rates of the rectus femoris (P = 0.015) between CD patients and controls, but no difference was found in serum vitamin D levels between groups (P = 0.317). Knee extension and flexion torque measurements, with age as a covariate, were compared with high and low vitamin D levels. Those subjects with high serum vitamin D levels had a significantly greater extension peak torque (P = 0.045) and extension average torque (Nm/kg) (P = 0.014) than those with low levels. Crohn's disease patients with sufficient vitamin D levels experienced a 43 % greater extension peak torque. Although vitamin D deficiency has been associated with neuromuscular dysfunction, there were no differences in serum vitamin D levels between the CD and healthy controls to explain the decreased muscle strength.