Endocrine Abstracts

Objective: Measuring thyroid stimulating hormone levels alone may be insufficient to appropriately evaluate thyroid function. Reduced thyroid stimulating hormone levels associated to normal/reduced FT₄ levels should prompt investigation of pituitary function.

Case: A 31-year-old man underwent biochemistry and thyroid function assessment for asthenia. He developed thyrotoxicosis due to painless thyroiditis with. positive.antithyroid antibodies. He had TSH level <0.010 mU/l (n: 0.35 to 4.9 mU/l), FT₄ level was 2.5 ng/dl (n: 0.7 to 1.5 ng/dl) and FT₃ level increased to 4.5 pg/ml (n: 1.7 to 3.7 pg/ml).

Subsequently 5 months later, we showed without any treatment reduced thyroid stimulating hormone levels associated to slightly decreased FT₄ levels and low-normal FT₃ levels. Endocrine assessment revealed deficiency in ACTH-cortisol, GH and IGF1 with hyperprolactinemia. Dynamic endocrine tests confirmed panhypopituitarism.

In fact, central hypothyroidism followed peripheral hyperthyroidism.

Magnetic resonance imaging showed a large pituitary tumor with cystic component with extension intra-and suprasellar suggestive of a craniopharyngioma.

The patient has a neurosurgical endoscopic transphenoidal allowing removal of the tumor and the histological analysis confirmed the diagnosis.

Conclusion: This association of peripheral hyperthyroidism with central hypothyroidism must be a rare occurrence, as a literature search has found only one case almost similar. Especially as the craniopharyngioma is a rare brain tumor and accounts for ~1.2–4.6% of all intracranial tumors. Our case illustrates coexistence of craniopharyngioma with hypopituitarism and clinically significant autoimmune thyroid disease. The presence of hypopituitarism does not preclude the development of autoimmune thyrotoxicosis.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.