Primary hyperparathyroidism after radioactive iodine therapy: Is it a distinct clinical entity?

BACKGROUND: Radioactive iodine (RAI) treatment is considered a rare cause of primary hyperparathyroidism (pHPT). METHOD: A multi-institutional retrospective review of patients with pHPT who underwent parathyroidectomy from 1990 to 2020 was completed to evaluate the prevalence and latency time for development of RAI-associated pHPT and determine clinical differences in pHPT patients with or without prior RAI treatment. RESULTS: 1929 patients with sporadic pHPT underwent parathyroidectomy; 48 (2.5%) had prior RAI treatment and 1881 (97.5%) did not. RAI treatment was for thyrotoxicosis in 43 (90%) patients. Average latency was 24 years (3-59 years) and inversely correlated with age. Patients with prior RAI treatment had lower preoperative calcium and PTH levels (p < 0.0001). No significant differences were observed in age, symptoms, pathology, ectopic glands and cure rate. CONCLUSION: RAI is a potential causative factor for pHPT, accounting for 2.5% of sporadic pHPT. RAI-associated pHPT may be a less severe form of sporadic pHPT and latency inversely correlates with age.

Clinical Study on Safety and Efficacy of Microwave Ablation for Primary Hyperparathyroidism.

OBJECTIVE: To evaluate the safety, feasibility, and efficacy of microwave ablation (MWA) for the treatment of primary hyperparathyroidism (PHPT). MATERIALS AND METHODS: This study enrolled 67 PHPT patients (22 men, 45 women; mean age, 56.0 ± 16.3 years; range, 18-83 years) from January 2015 to December 2018. The laboratory data, including the serum intact parathyroid hormone (iPTH), calcium, phosphorus, and alkaline phosphatase (ALP) levels, were evaluated before MWA and again 2 hours, 1 day, 7 days, 1 month, 3 months, 6 months, 12 months, 18 months, and 24 months after. RESULTS: Complete ablation was achieved with all 72 hyperplastic parathyroid glands found on the 67 patients enrolled, 64 of whom were treated in one session and 3 were treated over two sessions. The technical success rate was 100%. The median follow-up time was 13.6 months (range, 10.0-31.1 months). The clinical success rate was 89.4%. The volume reduction rate was 79.4% at 6 months. Compared to pre-MWA, the serum iPTH, calcium, phosphorus, and ALP levels had significantly improved 6 months post-MWA (iPTH, 157.3 pg/mL vs. 39.2 pg/mL; calcium, 2.75 ± 0.25 mmol/L vs. 2.34 ± 0.15 mmol/L; phosphorus, 0.86 ± 0.20 mmol/L vs. 1.12 ± 0.22 mmol/L; ALP, 79 U/L vs. 54 U/L, respectively; all, p < 0.01). Hoarseness was a major complication in 4 patients (6.0%), but it improved spontaneously within 2-3 months. CONCLUSION: MWA is safe, feasible, and effective for the treatment of PHPT.