MON-759 Evaluation of the Epidemiological, Clinical-Laboratory, and Genetic Profile in Severe Primary Hyperparathyroidism: 8 Years of Follow-Up

Abstract Disclosure: L.M. Santos: Sponsorship of Molecular Tests Conducted by Fleury Laboratory. T.W. Melero: Sponsorship of Molecular Tests Conducted by Fleury Laboratory. J.V. Lima: Sponsorship of Molecular Tests Conducted by Fleury Laboratory. N. Scalissi: Sponsorship of Molecular Tests Conducted by Fleury Laboratory. Severe primary hyperparathyroidism (SPH) is defined by serum calcium levels above 14 mg/dL and/or PTH (parathyroid hormone) exceeding 1000 pg/mL. Although rare, this condition is associated with a high risk of clinical complications, including bone disorders, nephrolithiasis, and renal dysfunction. This study aims to evaluate the epidemiological, clinical, laboratory, and genetic characteristics of patients with GHP over an eight-year follow-up period. This is a cross-sectional, observational study based on a review of electronic medical records of patients diagnosed with primary hyperparathyroidism (PHPT) between 2016 and 2024. Individuals with confirmed SPH and histopathological findings consistent with parathyroid adenoma were included. Genetic analysis targeted the following genes: AP2S1, CASR, CDC73, CDKN1B, GCM1, GNA11, MAX, MEN1, RET, SDHA, SDHAF2, SDHB, SDHC, and SDHD. Next-generation sequencing (NGS) was performed to identify pathogenic or likely pathogenic variants.A total of 117 individuals with PHPT were evaluated, with 90.5% being women (n=106) and 9.5% men (n=11). Of these, 69.2% (n=81) underwent surgical treatment, with histopathological findings showing adenomas in 69.1% (n=56), hyperplasia in 18.5% (n=15), and parathyroid carcinoma in 12.3% (n=10). The remaining 30.7% (n=36) continued with conservative management due to comorbidities, death, or loss to follow-up. The mean age at diagnosis was 59.4 ± 18.1 years for PHPT and 49.6 years for carcinomas. Among SPH patients (n=18), the mean (± SD) values at diagnosis were: age 54.5 ± 18.1 years, PTH 1160 ± 776.8 pg/mL (Ref: 12–88 pg/mL), and serum calcium 14.3 ± 1.4 mg/dL (Ref: 8.8–10.4 mg/dL). The most frequent complications among SPH patients included fractures and/or osteoporosis in 66.6% (n=12), nephrolithiasis in 72.2% (n=13), and hospitalization due to hypercalcemia in 61.1% (n=11). Brown tumors were identified in 50% (n=9), with 16.6% (n=3) located in the jaw. Acute kidney injury (AKI) was assessed according to KDIGO criteria, with a mean creatinine clearance (CKD-EPI) of 58.5 mL/min/1.73m². Severe dysfunctions, including the need for dialysis due to renal failure, nephrocalcinosis, and pancreatitis, were observed in 5.55% (n=1) of cases. Genetic analysis was performed in 11 out of 18 SPH patients, but no known pathogenic variants were identified.Although rare, parathyroid adenomas can exhibit aggressive behavior, leading to a higher rate of clinical complications. However, the low frequency of known pathogenic genetic variants suggests that other, yet unidentified, etiopathogenic mechanisms may be involved in SPH development. Further studies are needed to better elucidate these mechanisms. Presentation: Monday, July 14, 2025