VITAMIN-B-6, VITAMIN-C, AND CARPAL-TUNNEL SYNDROME - A CROSS-SECTIONAL STUDY OF 441 ADULTS

As part of an ongoing study of carpal tunnel syndrome (CTS) in industr y, we measured plasma concentrations of pyridoxal 5'-phosphate (PLP, a measure of vitamin B-6 status) and total ascorbate (ASC, a measure of vitamin C status) in 441 adult volunteers from six industries and a u niversity exercise study. In the entire study group and in non-vitamin users (n = 218), there were no significant differences in mean plasma PLP or ASC concentrations between. controls (neither symptoms nor slo wing), subjects with symptoms only, subjects with median nerve slowing only, or subjects with CTS (symptoms + slowing). In male non-vitamin users (n = 137), there were significant inverse univariate association s between plasma PLP concentration and the prevalence of pain, the fre quency of tingling and nocturnal awakening, and the Phalen test result . In this same subgroup, the ASC/PLP ratio was directly associated wit h the prevalence of pain and nocturnal awakening, and with the frequen cy of pain, tingling, and nocturnal awakening. rn multivariate analyse s, plasma ASC concentration predicted more median nerve slowing and co nfirmed CTS, and vitamin or vitamin interaction variables were indepen dent predictors of 20 CTS-related outcomes. These multivariate relatio nships often occurred only after adjustment for age, gender, body mass index, serum alkaline phosphatase activity, or tobacco use. We conclu de that there are significant relationships between plasma vitamin lev els and both components of CTS (specific symptoms and median nerve slo wing). The interaction between plasma PLP and ASC appears to be partic ularly important with respect to symptoms.