Endocrine Abstracts

Background: Primary hyperparathyroidism (PHPT) is a common endocrine disorder resulting from oversecretion of parathyroid hormone (PTH) in parathyroid glands. Hypocalcemia can occur in the postoperative period after parathyroidectomy (PTE) and can be challenging to control and requires varying doses of supplementation. Vitamin D deficiency can worsen the severity of PHPT and promote the development of “hungry bone syndrome” due to increased influx of calcium into bone after PTE.

Aim: To estimate the association of preoperative cholecalciferol therapy and development of hypocalcemia in 1–3 days after PTE in patients with PHPT.

Methods: Patients with PHPT, serum 25-hydroxyvitamin D (25(OH)D) <20 ng/ml (vitamin D deficiency), and serum total calcium <3 mmol/l were included. Exclusion criterion was the therapy with drugs affecting calcium-phosphorus metabolism – cinacalcet, denosumab or bisphosphonates (either as monotherapy or as a part of combination therapy). All patients underwent selective PTE at the Endocrinology Research Center in 1993–2010 or 2017–2020. PTH, total calcium, phosphorus were measured on 5 days – 4 years before surgery and before therapy by cholecalciferol (if any). 25(OH)D, alkaline phosphatase (AP), osteocalcin, c-terminal telopeptide of type 1 collagen (CTX-1) and dual-energy X-ray absorptiometry were measured on 4-365 days before surgery.

Results: Among 117 included patients, 110 (94%) were female and 7 (6%) male with median age 58 [49; 65] years. 21 patients took cholecalciferol for 2 weeks–2 months at a dose according to the replenishment of vitamin D deficiency and 96 did not. No significant difference was found in demographical (sex, age at surgery), clinical (severity of bone mass density loss) and laboratory parameters (PTH, total calcium, phosphorus, AP, osteocalcin, CTX-1, 25(OH)D) between these groups of patients. Patients with cholecalciferol therapy had significantly less frequent postoperative hypocalcemia (10% vs 63%, P<0.001, χ²). Cholecalciferol intake is negatively associated with hypocalcemia, RR=0.15, 95% CI: 0.03–0.51.

Conclusions: Taking cholecalciferol before PTE for 2 weeks–2 months reduces the risk of postoperative hypocalcemia by 2–33 times in patients with PHPT.