Vitamin D Concentrations and Neuromuscular Function in Patients with Crohn's Disease

Abstract

PURPOSE: The purpose of this study was to determine if patients with Crohn's disease have low serum vitamin D 25(OH)D and neuromuscular function, as evidenced by muscle strength, muscle fatigue, nerve function, and quality of health. METHODS: 19 subjects with Crohn's disease (9 M/10F, 44.2+10.3 yrs, 168.5+15.5 cm, and 77.2+19.5 kg ), with at least one small bowel resection were tested, as were 19 age and gender matched controls (44.21+10.41 yrs, 173.25+11.5 cm, and 80.5+17.3 kg). Serum vitamin D was measured via a blood draw. Isometric thigh muscle strength at 45° of knee extension were measured using a load cell in a custom device. Fatigue rates of the rectus femoris and vastus lateralis were assessed via EMG. Peroneal nerve latency and magnitude were measured with a Brevio® NCS-Monitor. The total physical score and total mental score from the SF-36 were also gathered to assess quality of health. A two factor ANOVA (group x gender) was performed on each of the measured variables (alpha = 0.05). RESULTS: No difference was found in the serum vitamin D concentrations between group (p=0.32) and gender (p=0.98). Quadriceps and hamstring peak torque (Nm/BW) was greater in the control group (p=0.039 and p=0.001, respectively). The males also demonstrated significantly greater knee extension (p=0.037) and flexion (p=0.047) peak torque. The fatigue rates for the rectus femoris and the vastus lateralis were not different between groups or genders. No group or gender differences were noted in nerve function or either quality of health measure of the SF-36. CONCLUSIONS: Low levels of serum vitamin D are known to negatively affect neuromuscular function. Although patients with Crohn's disease report muscle pain and weakness, they were not found to be low in vitamin D when compared to a healthy control group. Thigh muscle weakness was found for the Crohn's patients in the current study; however, this weakness is not believed to be related to low serum vitamin D levels. Further studies are required to identify the exact mechanisms of the decreased strength experienced by Crohn's patients.