Effects of Vitamin D Supplementation in Concomitant Primary Hyperparathyroidism and Vitamin D Deficiency
Review of the literature up to July 2010 revealed five studies that evaluated vitamin D therapy in patients with concomitant hypovitaminosis D and PHPT (Table).[15,24–27] Patients included in these trials had mild, mostly asymptomatic PHPT with serum calcium levels <12 mg/dL. Other important limitations include lack of randomization and, except in one study, absence of control subjects.[27] The overall results suggested that vitamin D supplementation in the setting of mild PHPT was safe. Meanwhile, the most common adverse effect of vitamin D therapy appeared to be an increase in urinary calcium, which reached statistical significance in two studies.[15,26] A fairly consistent finding after vitamin D therapy in the five studies was a mild decrease in serum PTH levels with mean reductions ranging from 3% to 25%, implying the coexistence of mild secondary hyperparathyroidism on top of PHPT.[15]
Two of the five studies evaluated the impact of vitamin D therapy on BMD. The first did not record significant effect on BMD in the lumbar spine and femoral neck in a subgroup of 12 patients after 12 months of vitamin D administration.[24] In the second study there was a significant increase in BMD at the lumbar spine and femoral neck in five patients who received calcium and vitamin D for five weeks.[15] The retrospective data of Grubbs et al[27] suggested that vitamin D replacement prior to parathyroidectomy had no significant effect on cure rates, frequency of recurrent disease, or occurrence of eucalcemic PTH elevation after parathyroidectomy.
South Med J. 2011;104(1):29-33. © 2011 Lippincott Williams & Wilkins
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