Navigating the rare intersection: parathyroid adenoma in a patient with pseudohypoparathyroidism

Rishi Iyer; Suhail Abdul-Wahab; Beenish Masood; Sulmaaz Qamar; Samuel Baxter; Eleni Armeni; Natalie Vanderpant; Quazi Islam; Bernard Khoo; Dipesh Patel; Efthimia Karra; Ahmed Yousseif

doi:10.1530/endoabs.109.P298

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Endocrine Abstracts (2025) 109 P298 | DOI: 10.1530/endoabs.109.P298

SFEBES2025 Poster Presentations Late Breaking (68 abstracts)

Navigating the rare intersection: parathyroid adenoma in a patient with pseudohypoparathyroidism

Rishi Iyer , Suhail Abdul-Wahab , Beenish Masood , Sulmaaz Qamar , Samuel Baxter , Eleni Armeni , Natalie Vanderpant , Quazi Islam , Bernard Khoo , Dipesh Patel , Efthimia Karra & Ahmed Yousseif

Author affiliations

Royal Free Hospital, London, United Kingdom

Introduction: We present a rare case of a 59 year old female patient with Albright’s Hereditary Osteodystrophy (AHO), a phenotype of pseudohypoparathyroidism (PHP), who developed a parathyroid adenoma. We aim to highlight the diagnostic and therapeutic considerations in managing the development of hypercalcaemia in the context of AHO/PHP.

Case: The patient was diagnosed with pseudohypoparathyroidism at age 33 after presenting with symptoms of hypocalcaemia. She exhibited phenotypic features of AHO, including an elevated BMI (34.5kg/m²) and short metacarpals, but genetic tests were negative. She was treated with alfacalcidol and cholecalciferol to maintain calcium at a target of 2.40mmol/L. DEXA scans indicated normal bone density and she did not develop nephrolithiasis. At age 51 she joined our service, and her albumin adjusted calcium (aaCa) level whilst on alfacalcidol ranged between 2.55 - 2.76 mmol/L. At age 58, the patient’s PTH level had risen to 26.8 pmol/L with an aaCa level of 2.67 mmol/L. Alfacalcidol was discontinued, but hypercalcemia persisted prompting further investigation. A whole-body SPECT CT scan showed no brown tumours. A parathyroid ultrasound localised a left inferior nodule, further corroborated on sestamibi scan, measuring 9x6x6 mm. There was a possible second, right inferior nodule that was equivocal. The multidisciplinary team concluded that the patient had developed a parathyroid adenoma, possibly due to tertiary hyperparathyroidism (THPT) in the context of PHP. She has since been managed with cholecalciferol alone and referred for consideration of parathyroid surgery.

Discussion: In more than 20% cases of THPT the underlying pathology has been observed to be a result of single or double parathyroid adenomas. Although PTH resistance is characteristic of PHP, hypercalcemia can occur due to partial resistance, potentially leading to THPT. In the context of PHP, elevated calcium levels should lead clinicians to consider the possibility of parathyroid adenoma development.