Endocrine Abstracts

Introduction: Hypocalcemia is a possible complication of thyroid surgery, usually assumed in the context of iatrogenic hypoparathyroidism. On the other hand, Hungry Bone Syndrome (HBS) is a complication classically described after surgical correction of primary hyperparathyroidism. It is characterized by hypocalcemia with normal or elevated PTH values (usually accompanied by hypophosphatemia and hypomagnesemia) and occurs consequently to a compensatory bone formation after a period of increased resorption. As increase bone resorption is present in hyperthyroidism, HBS can also follow hyperthyroidism surgery.

Methods: We retrospectively reviewed patients submitted to hyperthyroidism surgery in our center between 2020 and 2023. Exclusion criteria included concomitant hyperparathyroidism, bisphosphonate treatment, or previous therapy with radioactive iodine. Patients were subdivided into 2 subgroups; those who developed HBS (HBS+) and those who did not (HBS-). A comparative analysis including demographic, clinical and laboratory data was performed.

Results: A total of 98 patients were included. Thirteen patients underwent lobectomy (corresponding to toxic adenomas) and the remaining total thyroidectomy. The median age was 51±14 years, 85% were female patients (n=83). Thirty-five out of forty-seven patients (74%) who developed hypocalcemia (calcium <8,4 mg/dl) had normal or high PTH values (HBS+). Subgroups were similar for age at diagnosis, hyperthyroidism duration, medical treatment duration, initial values of TRABs (in patients with Graves’ disease), calcium, phosphorus and alkaline phosphatase. HBS + patients had higher fT4 (3.29 vs 2.6 ng/dl, P=0,06), ft3 (12.16 vs 10.78 ng/dl, P=0.29), and PTH (63 vs 48 pg/ml, P=0.037, n=25). Moreover, HBS+ patients needed higher doses of tiamazol (13 mg vs 9 mg, P=0,014).

Conclusion: In the current study, postoperative hypocalcemia was a common occurrence with most cases corresponding to HBS. Among those with hypoparathyroidism, there was recovery of hypocalcemia likely to correspond to transient hypoparathyroidism. Maximum needed tiamazol dosages and pre-operative PTH values were significantly different between HBS + and HBS- patients, suggesting that more severe hyperthyroidism is associated with HBS development.