[Association between preoperative cholecalciferol therapy and hypocalcemia after parathyroidectomy in patients with primary hyperparathyroidism].

Background: Primary hyperparathyroidism (PHPT) is a endocrine disorder characterized by excessive secretion of parathyroid hormone (PTH) from parathyroid gland tumors. Parathyroidectomy (PTE) is the main treatment for PHPT, but it can lead to hypocalcemia in up to 46% of cases. Hypocalcemia is associated with seizures and life-threatening cardiac arrhythmias, and vitamin D deficiency can exacerbate PHPT severity and contribute to «hungry bones syndrome,» resulting in severe and persistent postoperative hypocalcemia.

Aim: To evaluate the association and determine the strength of the relationship between preoperative cholecalciferol therapy and the occurrence of hypocalcemia within 1-3 days after PTE in patients with PHPT.

Materials and methods: The study was conducted at the Endocrinology Research Centre, during the periods of 1993-2010 and 2017-2020. The inclusion criteria consisted of patients diagnosed with PHPT who required PTE, had a serum 25-hydroxyvitamin D (25(OH)D) level below 20 ng/mL, and a serum total calcium level below 3 mmol/L. The exclusion criterion was the use of medications that affect calcium-phosphorus metabolism, including cinacalcet, denosumab, or bisphosphonates, either as monotherapy or as part of combination therapy.

Results: There were 117 patients, including 110 (94%) females and 7 (6%) males. The median age and interquartile range were 58 [49; 65] years. Among the participants, 21 (18%) received cholecalciferol supplementation for a duration of 2 weeks to 2 months prior to PTE, aiming to address vitamin D deficiency. The remaining 96 (82%) participants did not receive -cholecalciferol supplementation. Both groups, i.e., participants receiving cholecalciferol and those who did not, were similar in terms of anthropometric factors (sex and age at the time of surgery), preoperative clinical characteristics (BMD decrease), and laboratory parameters (PTH, total calcium, phosphorus, ALP, OC, CTX-1, and 25(OH)D levels). The occurrence of postoperative hypocalcemia was significantly lower in participants who received cholecalciferol supplementation (10% vs. 63%, p<0,001, FET2). Cholecalciferol intake showed a negative association with hypocalcemia development (RR=0,15, 95% CI (0,03; 0,51)).

Conclusion: Preoperative cholecalciferol supplementation for 2 weeks to 2 months before PTE reduces the risk of postoperative hypocalcemia in patients with PHPT by 2-33 times.