Normocalcemic hyperparathyroidism: Intervention to differentiate primary from secondary hyperparathyroidism.

BACKGROUND: Normocalcemic hyperparathyroidism can occur, but surgery should not be considered until common etiologies for secondary hyperparathyroidism are comprehensively excluded. Calcium deficiency is an underrecognized cause of normocalcemic parathyroid hormone elevation, and we aim to determine if the implementation of a preoperative calcium challenge can be used to reduce unnecessary parathyroidectomy. METHODS: Consecutive patients referred for parathyroidectomy (1/21-6/22) with normocalcemia (serum calcium <10 mg/dL) and concurrently elevated parathyroid hormone levels were routinely treated with supplemental calcium and vitamin D3, and follow-up laboratory studies were assessed. RESULTS: A total of 29/314 (9%) patients had normocalcemic parathyroid hormone elevation with mean calcium, parathyroid hormone, and vitamin D 25OH levels of 9.5 ± 0.3 mg/dL, 109.9 ± 34.9 pg/mL, and 42.7 ± 23.8 ng/mL respectively. Confounding factors included estimated glomerular filtration rate <60 in 2, loop diuretic use in 4, and prior gastric bypass or gastric sleeve surgery in 4. Follow-up biochemical evaluation was available in 27 (92%); results were unchanged in 7 patients (26%); normalization of parathyroid hormone levels with persistently normal calcium levels occurred in 15 (55%), thus confirming secondary hyperparathyroidism and hypercalcemia with elevated parathyroid hormone levels (classic primary hyperparathyroidism) was diagnosed in 5 (19%). Parathyroid exploration has been completed for 3 of 5 patients with classic primary hyperparathyroidism to date. CONCLUSION: A preoperative calcium challenge was prospectively initiated in normocalcemic patients with parathyroid hormone elevation, and there was high compliance (92%). Short-interval calcium supplementation revealed ∼50% to have resolved secondary hyperparathyroidism due to insufficient calcium intake, which avoided unnecessary surgery. In contrast, classic patients were unveiled in 20%, allowing for prompt and correct surgical intervention.

A comparative cost-utility analysis of postoperative calcium supplementation strategies used in the current management of hypocalcemia.

BACKGROUND: Symptomatic hypocalcemia is a common complication of total thyroidectomy. Management strategies include responsive treatment initiation for symptoms or prevention by routine or parathyroid hormone-directed calcium supplementation. The comparative cost-effectiveness of even the most often utilized strategies is unclear. METHODS: A Markov cohort model was created to compare routine supplementation with calcium alone (RS), postoperative parathyroid hormone-based selective supplementation with calcium and calcitriol (SS), and no supplementation (NS) in asymptomatic patients. Patients could remain asymptomatic or develop symptomatic hypocalcemia, managed with outpatient oral supplementation or intravenous calcium infusion and administered either inpatient or outpatient. Effectiveness was measured in quality-adjusted life years. Sensitivity analyses were performed to test model parameter assumptions. RESULTS: RS was the preferred strategy, costing $329/patient and resulting in 0.497 quality-adjusted life years, which was only marginally better compared to SS ($373 for 0.495 quality-adjusted life years). NS was most costly at $4,955 for 0.491 quality-adjusted life years. Preference for RS over SS was sensitive to the probability of developing symptoms and the probability of symptom treatment with intravenous supplementation. On probabilistic sensitivity analysis, RS was preferred in 75.4% of scenarios. CONCLUSION: After total thyroidectomy, a preventative calcium supplementation strategy should be strongly considered. In this data-driven theoretical model, RS was the least costly option and resulted in an incremental gain in quality-adjusted life years.