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Vitamin D deficiency in oncology patients--an ignored condition: impact on hypocalcemia and quality of life.

BACKGROUND
Vitamin D status is not evaluated routinely in cancer patients with bone metastasis who are treated with bisphosphonates.


OBJECTIVES
To assess the effect of vitamin D status on risk of hypocalcemia and quality of life in these patients.


METHODS
We performed laboratory tests for routine serum biochemistry, 25(OH)D, plasma parathyroid hormone (PTH) and bone turnover markers (CTX, P1NP) in 54 patients aged 57.5 +/- 13 years treated with intravenous bisphosphonates.


RESULTS
Most of the patients (n = 44, 77.8%) did not receive calcium and vitamin D supplementation. Their mean serum 25(OH)D levels (12.83 +/- 6.86 ng/ml) correlated with vitamin D daily intake (P = 0.002). In 53 patients (98.1%) 25(OH) D levels were suboptimal (< 30 ng/ml). Albumin-corrected calcium levels correlated with plasma PTH (P = 0.001). No correlation was observed between daily calcium intake and serum calcium (P = 0.45). Hypocalcemia was observed in one patient. Mean plasma PTH was 88.5 - 65 ng/L. Plasma PTH correlated negatively with 25(OH)D serum levels (P = 0.003) and positively with P1NP (P = 0.004). Albumin-corrected calcium correlated negatively with P1NP (mean 126.9 +/- 191 ng/ml) but not with CTX levels (mean 0.265 +/- 0.1 ng/ml) (P < 0.001). There was no correlation among quality of life parameters, yearly sun exposure and 25(OH)D levels (P = 0.99).


CONCLUSIONS
Vitamin D deficiency is frequent in oncology patients with bone metastasis treated with bisphosphonates and might increase bone damage. Our results indicate a minor risk for the development of severe hypocalcemia in vitamin D-deficient patients receiving bisphosphonate therapy. Although vitamin D deficiency might have some effect on the quality of life in these patients, it was not proven significant.