Endocrine Abstracts

JOINT251

Introduction: Autoimmune polyglandular syndrome type 2 (APS-2) is a rare endocrine disorder characterized by the coexistence of multiple autoimmune conditions, including type 1 diabetes, autoimmune thyroid disease, and others. Primary hyperparathyroidism (PHPT) is rarely associated with APS-2. This report discusses a complex case of APS-2 presenting with PHPT, illustrating the diagnostic challenges and therapeutic considerations.

Case Presentation: A 44-year-old female with a history of APS-2, including type 1 diabetes (diagnosed at age 10), autoimmune hypothyroidism, and premature ovarian insufficiency, presented for evaluation of hypercalcemia. Laboratory investigations revealed serum calcium at 111 mg/l, phosphorus at 27 mg/l, elevated parathyroid hormone (PTH) levels (twice the upper limit), and 24-hour urinary calcium excretion of 433 mg with fractional excretion of calcium exceeding 2%. Secondary causes were excluded through normal vitamin D levels and a 70 mL/min glomerular filtration rate. Imaging identified a right inferior parathyroid adenoma. Further evaluations ruled out multiple endocrine neoplasia (MEN) syndromes. Bone densitometry demonstrated femoral and lumbar osteoporosis, but there was no renal or cardiac damage. The patient was referred for surgical management of PHPT.

Discussion: PHPT in APS-2 is an uncommon finding, often masked by overlapping autoimmune conditions. This case emphasizes the importance of considering hypercalcemia and evaluating PTH in APS-2 patients presenting with osteoporosis or other metabolic bone diseases. The literature highlights the role of autoimmunity in parathyroid dysfunction, including potential contributions of anti-calcium-sensing receptor autoantibodies. While rare, PHPT should prompt careful screening to avoid misdiagnosis or delayed treatment.

Conclusion: This case underscores the complexity of diagnosing and managing APS-2 with PHPT. Multidisciplinary approaches are crucial to address the interplay of autoimmune conditions, ensuring timely diagnosis and optimal outcomes. Further research is needed to explore the prevalence and pathophysiological mechanisms linking PHPT and APS-2.