Endocrine Abstracts

Introduction: Calcium and vitamin D (CaD3) supplementation is routinely offered to care home residents in the UK to treat prevalent vitamin D insufficiency. However, blanket prescribing may be ineffective where secondary hyperparathyroidism is due to chronic kidney disease (CKD) and dangerous if undiagnosed primary hyperparathyroidism is present. In this base-line audit, we aimed to estimate the frequency and appropriateness of CaD3 prescription, and the prevalence of primary and secondary hyperparathyroidism.

Methods: We recruited 109 subjects (67% female) with a mean age of 84 years, admitted to clinical decisions unit from residential or nursing homes. Estimated GFR (eGFR), bone chemistry and iPTH were measured.

Results: CaD3 was already prescribed in 43% patients on admission. PTH was measured in 81 subjects and was raised in 32 (40%). PTH was raised in 31% of those on CaD3; 48% of those untreated and in eight of 18 patients with stage 4 or 5 CKD. Based on plasma calcium and PTH levels, 16% had primary hyperparathyroidism and 28% had probable vitamin D deficiency. Hypercalcaemia (P<0.01) but not hypocalcaemia (P=0.34) was significantly more frequently seen in CKD. Forty-one patients were offered CaD3 therapy and, of 15 patients who had serial PTH measurement, PTH was suppressed by 0.022 pmol/L (P<0.05) after 3 months.

Discussion: Higher rates of both primary hyperparathyroidism and CKD are seen than in the general population. Two fifths of residents had a raised PTH. Most of those with stage 4/5 CKD were already treated with CaD3 (although they were unlikely to be able to metabolise vitamin D3). However, it was not clear in those with hyperparathyroidism, whether renal impairment or vitamin D deficiency were responsible. Thus, blanket prescribing of CaD3 may be ineffectual in those with stage 4 or 5 CKD and put some subjects with primary hyperparathyroidism at risk of hypercalcaemia.