Endocrine Abstracts

Introduction: Primary hyperparathyroidism (PHPT) is the third most common endocrine disorder; its evaluation includes biochemical investigations and imaging studies prior to surgical intervention. Imaging is advised as an aide to surgery and not for diagnostic purposes. Coexistence of PHPT and vitamin D deficiency is common; however, the exact nature of the relationship (causal vs secondary) is not clear.

Subject and methods: We conducted a retrospective review of data of 122 patients referred for sestamibi parathyroid scan over a period of 2 years. Objectives included review of the diagnosis, outcomes, associated vitamin D deficiency and appropriateness of imaging requests.

Results: Of 122 patients, 101 (82.78%) were diagnosed as PHPT. Ninety-eight (80.33%) were operated and 86 (87.76%) had good outcome with no recurrence. Out of 74 patients with PHPT who had their vitamin D levels checked prior to imaging, 26 (35.13%) had vitamin D insufficiency (<20 ng/ml or 50 nmol/l) and 20 (27.02%) were vitamin D deficient (<10 ng/ml or 25 nmol/l). Secondary causes of hyperparathyroidism were found in 17 patients; 15 were due to vitamin D deficiency and 2 were related to chronic kidney disease (CKD). Other causes of hypercalcaemia included 1 patient each with familial hypocalciuric hypercalcaemia (FHH), hypercalcaemia of malignancy and tertiary hyperparathyroidism. Nineteen patients (15.57%) were inappropriately referred for imaging studies and mostly included cases of secondary hyperparathyroidism (except 1 each of FHH and hypercalcaemia of malignancy).

Conclusion: Concomitant vitamin D deficiency or insufficiency is common in patients with PHPT and the combined prevalence was estimated as 62% in our study. To avoid unnecessary imaging in patients with PHPT, we recommend that imaging studies should be arranged only by the endocrinology team, after biochemical confirmation and once surgery is planned.