Calcitonin levels and pseudohypoparathyroidism: understanding the connection

Bojan Markovic; Mirjana Stojkovic; Sanja Klet; Tamara Janic; Jovana Babic; Biljana Beleslin; Jasmina Ciric; Milos Zarkovic

doi:10.1530/endoabs.101.PS3-26-02

PS3-26-02

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Endocrine Abstracts (2024) 101 PS3-26-02 | DOI: 10.1530/endoabs.101.PS3-26-02

ETA2024 Poster Presentations Miscellaneous (6 abstracts)

Calcitonin levels and pseudohypoparathyroidism: understanding the connection

Bojan Markovic ¹ , Mirjana Stojkovic ² , Sanja Klet ³ , Tamara Janic ⁴ , Jovana Babic ⁵ , Biljana Beleslin ⁶ , Jasmina Ciric ⁷ & Milos Zarkovic ⁸

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¹Clinic of Endocrinology, Diabetes and Metabolic Diseases, University Clinical Center of Serbia, Clinic for Endocrinology, Diabetes and Diseases of Metabolism, University Clinical Centre, Belgrade, Serbia, Thyroidology, Belgrade, Serbia; ²Clinic of Endocrinology, Diabetes and Metabolic Disease, University Clinical Center of Serbia, Faculty of Medicine, University of Belgrade, Clinic of Endocrinology, Diabetes and Metabolic Diseases, University Clinical Center of Serbia, Belgrade, Serbia; ³Clinic of Endocrinology, Diabetes and Metabolic Diseases, University Clinical Center of Serbia, Dr Subotic 13, Thyroidology, Belgrade, Serbia; ⁴Clinic of Endocrinology, Diabetes and Metabolic Disease, University Clinical Center of Serbia, Clinic of Endocrinology, Diabetes and Metabolic Diseases, University Clinical Center of Serbia, Thyroidology, Belgrade, Serbia; ⁵Clinic of Endocrinology, Diabetes and Metabolic Diseases, University Clinical Center of Serbia, Serbia; ⁶Clinic of Endocrinology, Kcs, Medical School Belgrade, Clinical Center of Serbia, Belgrade, Serbia; ⁷Clinic of Endocrinology, Diabetes and Metabolic Diseases, Clinical Center of Serbia, Medical School University of Belgrade, Department for Thyroid Diseases, Belgrade, Serbia; ⁸Faculty of Medicine, University of Belgrade, Belgrade, Serbia, Faculty of Medicine, University of Belgrade, Faculty of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, Serbia

Background: Pseudohypoparathyroidism (PHP) is a genetic disorder characterized by resistance or an inappropriate response in specific G protein receptors. The pathophysiology of PHP type 1-a involves an autosomal dominant mutation of the GNAS complex locus. A classic triad of abnormality includes hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone (PTH) concentrations. Additionally, other hormonal imbalances can occur in PHP and higher calcitonin levels have been described in patients with type 1-a.

Case Report: A 37-year-old male presented with persistently elevated calcitonin levels, and the ultrasound showed a normal-sized thyroid gland without nodules or pathological lymph nodes. He was diagnosed with pseudohypoparathyroidism type 1-a based on the presence of Albright’s hereditary osteodystrophy (AHO) features: obesity, short stature, radiography confirmed shortened IV and V metacarpal bones, subcutaneous calcifications and developmental delay. Additionally he exhibited vascular calcium deposits, particularly in the basal ganglia (Fahr syndrome). Genetic testing is unknown. Besides elevated levels of thyroid-stimulating hormone (TSH: 9.26-9.38 mIU/l), parathyroid hormone (PTH: 492-245 pg/ml), basal calcitonin levels were significantly high (2015: 107 ng/l; 2019: 111.2 ng/l; 2023: 94 ng/l). Given calcitonin’s role as a tumor marker for medullary thyroid carcinoma (MTC), a calcium stimulation test with serial calcitonin measurements were performed (0, 1, 3, 5, and 10 minutes): CT 187, 1; 2480; 2381; 1993; 1337 ng/l. Other tumor markers such as carcinoembryonic antigen, neuron-specific enolase and chromogranin A, were negative.

Conclusion: Elevated calcitonin levels should be investigated through clinical examination, including morphological and functional tests, as this marker strongly indicates the presence of MTC and some neuroendocrine tumors. The observed high hormone and calcitonin levels in our patient are likely due to the molecular mechanisms of multiple receptor resistance. After nearly ten years of follow-up, our patient did not have MTC, which was confirmed by both clinical evaluation and ultrasound imaging. As some authors recommend, fine-needle aspiration biopsy for patients with nodules can minimize the risk of missing medullary thyroid cancer.