Low serum vitamin D occurs commonly among multiple myeloma patients treated with bortezomib and/or thalidomide and is associated with severe neuropathy.

PURPOSE: Previous studies have shown that low serum vitamin D levels have been associated with many skeletal and non-skeletal disorders. We studied the relationship between 25-hydroxyvitamin D (25D) levels and motor and sensory peripheral neuropathy (PN) among multiple myeloma (MM) patients who have been treated with bortezomib and/or thalidomide.
METHODS: We performed a study of 111 MM patients who had received at least one of these two agents for at least 12 weeks by correlating physical exam/neurologic assessment findings with patient self-assessment responses.
RESULTS: The median age of study patients was 66 years (range 42-89 years) and 54 % were males. 25D levels were determined, and complete history and physical and neurologic examinations were performed at the same study visit. In addition, study subjects completed questionnaires regarding symptoms related to motor and sensory PN. Overall, patients had a median serum 25D level of only 32 ng/ml; 42 % of patients were considered either 25D-deficient (<20.0 ng/mL; 16 % of patients) or 25D-insufficient (20.0-29.9 ng/mL; 26 %). Notably, we found that 25D-deficient MM patients were more likely to have severe PN (>grade 2) of both motor (p = 0.0415) and sensory (p = 0.0086) types although the overall incidence of PN was not higher in this patient population.
CONCLUSION: These results show that the severity of peripheral neuropathy is associated with lower vitamin D levels and provides the rationale for monitoring vitamin D for myeloma patients especially those receiving drugs associated with the development of peripheral neuropathy.