Clinical and Biological Features of Primary Hyperparathyroidism in Multiple Endocrine Neoplasia Type 2A: A Retrospective Study of Five Cases

Abstract Introduction: Multiple Endocrine Neoplasia type 2A (MEN2A) is a rare genetic disorder primarily characterized by Medullary Thyroid Carcinoma (MTC) and Primary Hyperparathyroidism (PHPT) in 20 to 30% of cases. PHPT is rarely the initial presenting symptom. This study aims to describe the clinical and biological features of PHPT in MEN2A to improve understanding and management of this condition. Patients and Methods: This is a retrospective descriptive study over seven years, including five patients harboring RET gene mutations diagnosed with MEN2A and PHPT, followed at the Endocrinology Department of Ibn Sina University Hospital, Rabat. Results: The mean age at PHPT diagnosis was 26.8 years. One case of renal lithiasis and one case of bone fracture were reported. The mean Parathyroid Hormone (PTH) level was elevated at 182.2 pg/ mL, with a normal mean serum calcium of 101.2 mg/L. Parathyroid ultrasound revealed lesions in all cases, leading to parathyroid surgery involving excision of one to three glands. Discussion and Conclusion: PHPT associated with MEN2A presents specific clinical features, including a high frequency of normocalcemic forms possibly related to prevalent vitamin D deficiency. Systematic screening is essential for early diagnosis and appropriate management. This study highlights the importance of rigorous monitoring protocols in this at-risk population.