Management of hypovitaminosis D in patients with primary hyperparathyroidism

Epidemiological studies suggest that vitamin D deficiency is common in patients with primary hyperparathyroidism (PHPT). They have higher levels of serum parathyroid hormone (PTH) and markers of bone turnover and fractures are more frequent than vitamin D-replete patients. However, there are concerns that Vitamin D repletion might exacerbate pre-existent hypercalcaemia. Therefore, we aimed to determine if vitamin D replacement improved biochemical indices of calcium metabolism without worsening underlying hypercalcaemia.

This is a prospective, observational study based on routine clinical practice, set up in a secondary care centre. 45 consecutive patients with mild biochemical hypercalcaemia due to PHPT and hypovitaminosis D were enrolled. The mean age of the cohort was 61 years (range 25-85 years), predominately Asian (32 patients) and female (41 patients). They received 20,000 IU of oral cholecalciferol, once a week, for 3 months. Calcium, phosphate, alkaline phosphatase and PTH were measured at baseline, 4, 8 and 12 weeks following treatment. Vitamin D levels were obtained at baseline and at 12 weeks, after they completed their treatment.

Vitamin D levels normalised at week 12 (mean ± SD, 18.8 ± 9.4 versus 76 ± 20 nmol/L, p = 0.0001) and PTH levels improved following treatment completion (21.2 ± 10 versus 16.2 ± 6 pmol/L, p = 0.026). There was no significant increase in serum calcium levels during vitamin D supplementation.

High doses of oral cholecalciferol normalised vitamin D levels without worsening underlying hypercalcaemia in individuals with PHPT.