SAT-761 The Largest Study (LATVPHPT) on Primary Hyperparathyroidism Conducted at Riga East University Hospital, Latvia: Part Two

Abstract Disclosure: D. Sturite: None. I. Rasa: None. Background: . Primary hyperparathyroidism (PHPT) can present a wide range of clinical symptoms, varying from asymptomatic to those with significant involvement of multiple organs. The literature shows variability in the prevalence of organ involvement and related conditions. Methods: . This LATVPHPT study included 177 PHPT patients diagnosed between January 1, 2021, and January 1, 2024. Using IBM SPSS 29.0 software, we conducted a detailed retrospective analysis of medical records, laboratory data, radiologic findings, surgical outcomes, and histopathology reports. Results: . 177 patients (mean age 63.8±11.9 years), 89% were females. 65% (n=115) of patients underwent parathyroidectomy, 14.7% (n=26) had surgery postponed due to unknown adenoma location, 1.1% (n=2) declined, 19.2% (n=34) - awaiting surgery, 3 - needed reoperation due to negative histopathology. Hungry bone syndrome occurred in 3 patients. 2 patients had MEN1 syndrome. Histopathological analysis and imaging in patients who underwent surgery identified a single adenoma in 94.0% (n=108), double adenomas - 1.7% (n=2), hyperplasia - 2.6% (n=3), carcinoma - 1.7% (n=2), and ectopic adenomas in 6.1% (n=7), with locations including intrathyroidal (n=3), anterior mediastinum (n=2), para jugular (n=1), superior posterior mediastinum (n=1). Among imaging modalities, contrast-enhanced ultrasonography (CEUS) showed superior performance compared to ultrasonography (b = −1.68, p = 0.020), scintigraphy (b = −1.70, p = 0.026), and 3D-CT (b = −1.66, p = 0.046). While SPECT/CT demonstrated a similar trend, the results did not reach statistical significance (b = −1.2, p = 0.099). The mean preoperative calcium was 2.9±0.3mmol/L, intact parathyroid hormone (iPTH) - 251.2±242.1pg/mL, phosphorus - 0.8±0.2mmol/L, 25-OH vitamin D - 27.6±13.3ng/mL. The mean postoperative calcium was 2.4±0.1mmol/L, iPTH - 59.9±36.5pg/mL, phosphorus - 1.1±0.2mmol/L, 25-OH vitamin D - 43.4±16.1ng/mL. Comorbid conditions included osteoporosis in 35% (n=62), osteopenia in 54% (n=95), and osteoporotic fractures in 15% (n=26). 17.5% (n=31) of patients received oral bisphosphonates, 4.0% (n=7) - intravenous bisphosphonates, 8.5% (n=15) - denosumab, 1.1% (n=2) - medication holidays. 25% (n=44) had kidney stones, 23% (n=41) - gallstones. Thyroid conditions included thyroid nodules in 81% (n=143), nontoxic goitre in 53% (n=93), and autoimmune thyroiditis in 29% (n=51). Other associated conditions included hypertension 43% (n=76), type 2 diabetes 14% (n=24), and malignancies 20% (n=36), most commonly breast and thyroid cancers. Conclusions: High rates of skeletal complications and malignancies in PHPT emphasize its clinical impact. Precise imaging, timely diagnosis, and appropriate treatment are essential for managing its complex manifestations. Presentation: Saturday, July 12, 2025