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Vitamin D Deficiency May Cause Skeletal Complications In Multiple Myeloma Patients

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Published: Jul 25, 2009 5:06 pm

Vitamin D deficiency may be a significant cause of skeletal complications in multiple myeloma patients, according to a recent study published in the American Journal of Hematology. Skeletal complications, which include hypercalcemia (high calcium levels), bone loss, and osteolytic bone lesions, are a major cause of morbidity in multiple myeloma.

"Bone health is very important for quality of life in patients with myeloma, due to lytic lesions and an increased risk of fracture," explains Dr. Matthew Drake, an author of the study. "Vitamin D is very important for maintaining skeletal health, and in combination, vitamin D and adequate calcium intake have been found to limit bone loss in patients without myeloma."

Vitamin D functions as a key mediator in skeletal metabolism by stimulating the absorption of calcium and phosphate in the intestines and by promoting bone mineralization. Consequently, a deficiency in vitamin D may result in reduced intestinal calcium absorption and secondary hyperparathyroidism.

Hyperparathyroidism results when the parathyroid glands secrete excessive amounts of parathyroid hormone (PTH) in response to hypocalcemia (low serum calcium levels) and hyperphosphatemia (high serum phosphate levels). In order to maintain normal serum calcium levels, skeletal catabolism (or breakdown) often increases. Additionally, studies have recently found that vitamin D inhibits carcinogenesis, which is the process by which normal cells turns cancerous.

Based on the known functions of vitamin D, researchers have speculated that vitamin D deficiency may contribute to both skeletal complications and to the progression of multiple myeloma. In order to further examine the association between vitamin D levels and multiple myeloma, the current study tracked the vitamin D levels of 148 patients with newly diagnosed myeloma for five years. A vitamin D deficiency was defined by a serum vitamin D concentration of less than 50 nmol/L.

Twenty-four percent of patients in the study were vitamin D deficient. These patients had higher levels of serum C-reaction protein (CRP) and creatinine, which studies have associated with a poorer multiple myeloma prognosis.

The study also found a “step-wise” relationship between vitamin D deficiency and the International Staging System (ISS), which outlines criteria for each stage of multiple myeloma. At initial diagnosis, patients deficient in vitamin D were more likely to receive higher ISS stagings. Given that ISS staging is important at indicating multiple myeloma prognosis, this result suggests that vitamin D deficiency may predict a poor prognosis in multiple myeloma.

The results of this study stress the widespread implications of vitamin D deficiency in multiple myeloma prognosis. However, the study population included predominantly Caucasian patients, and further investigation is needed to confirm that these results are applicable to other ethnic groups.

Drake told The Myeloma Beacon that current recommendations are for 800-1200 international units of Vitamin D daily. "This amount of vitamin D is often difficult to get by dietary sources alone and often requires some supplementation in the form of a multivitamin (often containing 400-800 IU vitamin D) or vitamin D itself," he said. "Either D2 (ergocalciferol) or D3 (cholecalciferol) containing sources can be used for supplementation."

For more information, please see the full study in the American Journal of Hematology (pdf).

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