Endocrine Abstracts

JOINT2024

Introduction: Calcitonin (CT) is essential for diagnosing medullary thyroid carcinoma (MTC), with levels >100 pg/ml being highly predictive, though elevated CT is not a pathognomonic factor of MTC. Hypercalcitoninemia has also been linked to conditions like hypercalcemia, hypergastrinemia, renal insufficiency, neuroendocrine tumors, other thyroid carcinomas, prolonged use of certain medications. Chronic autoimmune thyroiditis (AIT) may elevate CT, but its impact on hypercalcitoninemia is unclear. Investigating slightly elevated CT is important for determining treatment, whether monitoring thyroid-related disorders, addressing malignancies or benign conditions like AIT.

Case: A 22-year-old female (BMI 40.9) visited an endocrinologist due to hypercalcitoninemia found after detailed laboratory blood tests performed at the patient’s initiative. Family history: thyroid disease, diabetes. In 2023, neck ultrasound showed normal-sized hypoechogenic thyroid with heterogeneous structure, connective tissue degeneration, normal blood flow. No pathological lymph nodes were observed. Both in 2023 and 2025 performed neck ultrasound suggested AIT. In 2025, the patient’s thyroid fulfilled EU-TIRADS 2 criteria. Laboratory tests showed fluctuating CT levels from year 2023 to 2025 from 7.02 to 30.07 pg/ml (n. r.<5.89, Table 1). Following tests were within reference ranges: TSH, FT4, FT3, anti-TPO, anti-Tg, anti-TSRH, CEA. Due to low vitamin D (35.5 nmol/l, n. r.125-150), vitamin D3 was taken at 8000 IU/day for 3 months, then reduced to 4000 IU/day permanently. Since anti-TPO and anti-Tg antibodies were within normal limits, elevated CT cannot be linked to AIT. With no clinical signs of thyroid dysfunction, no treatment was prescribed. Blood calcium level, other electrolytes examined were within normal limits. No changes were observed on chest X-ray and abdominal ultrasound. Tests for adrenal conditions detected no pathology. Consequently, other endocrinological causes of hypercalcitoninemia were excluded. Currently, the patient is diagnosed with non-toxic multinodular goiter. Check-up is recommended after 6 months.

Discussion: This case emphasizes the need to consider both common and rare causes and conduct a thorough evaluation when managing hypercalcitoninemia. Elevated CT levels should be assessed within the full clinical context. An aggressive approach may be unnecessary in patients with marginal increase in CT levels after excluding causes of hypercalcitoninemia demanding specific treatment. Adequate follow-up with serum CT measurement and thyroid ultrasound can prevent missing clinically significant MTC.

References: 1. Kiriakopoulos A, Giannakis P, Menenakos E. Calcitonin: current concepts and differential diagnosis. Ther Adv Endocrinol Metab. 2022;13:20420188221099344.