Endocrine Abstracts

Introduction: Eighty percent of patients with PHPT have co-existing vitamin D deficiency. Few large studies have assessed the impact/safety of different vitamin D preparations on calcium, PTH and vitamin D in such patients. We report the use of three different preparations.

Methods: In a retrospective study of 125 patients with confirmed PHPT, 77% were vitamin D deficient (<30 nmol/l)/insufficient (30–50 nmol/l). We assessed the impact and safety of treatment with vitamin D3 or D2 (50 000 IU) after 48 weeks (n=35), calcium and vitamin D (e.g. Adcal-D3) twice daily for 3 months (n=16) and over the counter (OTC) vitamin D 1000 IU/day (n=41) for 3 months on calcium, PTH and vitamin D levels. In four patients, the Vitamin D preparations were unspecified.

Results: See Table. Mean (±S.D.) serum calcium remained stable after treatment for whole group (2.75 (±0.22) vs 2.74 (±0.24) mmol/l; P=0.699).

Conclusion: Vitamin D repletion, regardless of regimen, in patients with PHPT and Co-existing vitamin D deficiency is safe and does not significantly exacerbate hypercalcaemia for the majority of patients. Patients treated with combined calcium and vitamin D preparations had lower baseline calcium, but calcium levels still did not rise significantly with treatment.

Finally, despite the increased metabolism of vitamin D in PHPT, most patients were replete within 3–6 months regardless of vitamin D preparation.