Endocrine Abstracts

JOINT2228

Hypoparathyroidism (HypoPT) is a rare endocrine disorder characterized by hypocalcemia and absent, low, or inappropriately normal PTH levels. The most common cause is neck surgery (75%), while nonsurgical forms, including idiopathic and genetically determined HypoPT, account for the remaining 25%. These forms are rarer and less well understood. This retrospective study investigates the clinical and biochemical characteristics, as well as complications, in 26 patients with idiopathic or genetically determined HypoPT followed at our Endocrinology Unit. We included 26 patients (15 women, 11 men) with a mean age at diagnosis of 22±14 years (5–59) and a mean disease duration of 10. 8±11 years (1–48). Genetic screening identified pathogenic variants in seven patients: five deletions of 22q11. 2 (DiGeorge syndrome), one GATA variant associated with hypoparathyroidism, sensorineural deafness, and renal dysplasia (HDR) syndrome, and one AIRE variant (APS type 1). Two variants of uncertain significance in GCM2 and AIRE genes and one benign GNAS variant was identified. The remaining patients had no detectable mutations. The mean daily calcium and calcitriol supplementation was 1200 mg (0–3000) and 0. 9 µg/day (0. 5–1. 5), respectively. Despite treatment, 10 patients (38. 5%) experienced hypocalcemic symptoms. Baseline biochemical tests showed mean albumin-corrected serum calcium of 9. 04 ± 0. 6 mg/dL (7. 5–11. 3), phosphorus 3. 5 ± 0. 58 mg/dL (2. 2–6. 2), ionized calcium 1. 19 ± 0. 08 mmol/l (0. 93–1. 53), and magnesium 1. 9 ± 0. 14 mg/dL (1. 4–2. 5). Mean urinary calcium excretion was 255 mg/day (156–387). Corrected calcium, phosphorus, and magnesium levels were within target in 62%, 65%, and 53% of patients, respectively. Complications included basal ganglia calcifications (46. 2%), audiometric abnormalities (34. 6%), cardiac alterations (7. 7%), and recurrent infections (15. 4%). Renal involvement was observed in 46% of patients, with eight cases of nephrolithiasis and four of renal insufficiency. Reduced bone mass was documented in only one patient, and one vertebral fracture was reported. Bone evaluation showed a mean lumbar spine BMD of 1. 176 g/cm² (T-score 1. 2, Z-score 1. 2); a mean femoral neck’s BMD of 1. 003 g/cm² (T-score 0. 5, Z-score 0. 7); a mean total hip’s BMD of 1. 059 g/cm² (T-score 0. 5, Z-score 0. 7) and a mean one-third radius’ BMD of 0. 705 g/cm² (T-score -0. 7, Z-score -0. 3). These findings highlight the heterogeneity of disease and its complications in patients with non-surgical HypoPT. Furthermore, many patients fail to achieve optimal biochemical targets despite treatment. This underlines the need for further studies to better understand this condition and develop improved therapeutic strategies to optimize patient outcomes.