Efficacy of vitamin D supplementation in deficient multiple myeloma patients

Randomized controlled studies have shown that the introduction of the 'new agents' bortezomib, thalidomide and lenalidomide resulted in improved response, progression-free survival and overall survival. However, vitamin D-deficiency is a frequent problem for patients with multiple myeloma. In addition, there is a high prevalence of peripheral neuropathy among these patients. Several studies have shown that an adequate vitamin D level has several advantages for the human body, such as improvement of the muscle function and the immune system. Obtaining an adequate vitamin D level in patients with multiple myeloma is therefore a major gain in which the quality of life can improve or decrease less quickly. Vitamin D-deficiency is also associated with many complications, such as a decrease in bone density and possibly peripheral neuropathy.
Vitamin D could potentially be used to prevent peripheral neuropathy in patients with multiple myeloma.

Supplementation of vitamin D in vitamin D-deficient multiple myeloma patients following a predifined vitamin D dosing regimen will result in adequate vitamin D levels in these patients

At the start of the study patients will get an intake in which a vitamin D loading dose (200.000 IE) will be given. In addition, patients start with 800IE of vitamin D once daily. After 2 months, blood samples will be taken and the ICPNQ questionnaire and VAS scores will be completed. If vitamin D levels are below 75 nmol/L, another loading dose will be given and vitamin D doses will be increased to 1600IE. The vitamin D levels of these patients will be measured again after three months. If vitamin D levels are still below 75 nmol/L, vitamin D doses will be increased again to 3200 IE. After six months, vitamin D will be measured and the ICPNQ Questionnaire and VAS scores will be completed.

Patients receive vitamin D-supplements for six months and will receive a vitamin D loading dose (may be repeated after two months). In addition, every patient will complete the ICPNQ Questionnaire and VAS scores after 2 and 6 months to determine neuropathy grading. After 2 (, possibly 3) and 6 months blood samples will be taken.