Endocrine Abstracts

JOINT3057

Introduction: Severe hypothyroidism is a rare but possible endocrine complication following chemotherapy. It may be linked to an autoimmune thyroiditis triggered by cytotoxic agents. This poster presents a case of severe thyroid dysfunction in the context of post-chemotherapy follow-up for Ewing’s sarcoma.

Clinical Case: We report the case of a 24-year-old patient followed for Ewing’s sarcoma of the jaw, who underwent surgery, followed by a pulmonary metastatic relapse. The patient had surgery and adjuvant chemotherapy, and was referred for exploration of thyroid hypermetabolism discovered during a PET scan performed as part of the staging assessment. Laboratory tests revealed a TSH > 100 µUI/ml and positive anti-thyroglobulin antibodies, compatible with severe hypothyroidism. A cervical ultrasound showed signs of thyroiditis. Management consisted of introducing hydrocortisone at 10 mg/day for 5 days, followed by a gradual introduction of levothyroxine to an optimal replacement dose. Clinical and biological monitoring allowed for gradual improvement in hormonal parameters and symptoms.

Scientific Discussion: Although chemotherapy is necessary to treat aggressive malignant conditions, it can trigger thyroid inflammation through immune mechanisms, notably by the production of anti-thyroid antibodies such as anti-thyroglobulin and anti-thyroid peroxidase antibodies, which damage the gland and induce hypothyroidism. It can also have a direct toxic effect due to the use of certain chemotherapy agents, such as alkylating agents and anthracyclines. Management of this condition relies on thyroid hormone replacement with levothyroxine, with a cautious approach depending on the severity of the dysfunction.

Conclusion: Hypothyroidism is a recognized complication of chemotherapy, often underdiagnosed. This case highlights the importance of screening for thyroid dysfunction in patients who have received treatments likely to affect thyroid function, particularly aggressive treatments like alkylating agents, and especially when atypical symptoms or suggestive imaging findings are present. Prompt and appropriate management helps prevent complications and significantly improves the patients’ quality of life.