Introduction: Studies suggest that vitamin D has a role in neuroprotection. Low vitamin D is related to neuropathy in patients with diabetes, Sjögren’s syndrome and other neurodegenerative disorders. However, no study has been conducted measuring serum vitamin D levels in patients with CTS. The aim of this study was to investigate whether vitamin D status is associated with CTS, by comparing vitamin D levels between CTS patients and healthy control women and between patients with CTS and other upper limb conditions. Methods: Vitamin D levels were compared between carpal tunnel syndrome women (n = 135) and healthy control women (n = 135) or patients with other upper limb conditions (n = 135). Results: There were no differences in vitamin D levels between the patients with carpal tunnel syndrome and the controls. However, women with carpal tunnel syndrome younger than 50 years old had significantly lower vitamin D levels than age-matched healthy control women (P = 0.023) or patients with other upper limb conditions (P = 0.035). When women with carpal tunnel syndrome and healthy control women were pooled, the incidence of carpal tunnel syndrome was higher in vitamin D deficient women than in non-deficient women, especially in those younger than 50 years. Discussions: This study suggests a potential link between vitamin D status and the occurrence of carpal tunnel syndrome in women younger than 50 years but causation is not established.
