| Secondary or central hypothyroidism is very rare and accounts for less than 1% of the cases of thyroid insufficiency in adult. Pituitary hypothyroidism is often integrated in total or partial hypopituitarism due to various causes: adenomas of the secreting or non-secreting type, craniopharyngioma, intrasellar meningioma, metastatic tumors, autoimmune hypohysitis, post-partum Sheehan's syndrome, partial empty sella syndrome, sarcoidosis, histiocytosis X, hemochromatosis, infections, or may be iatrogenic (hypophysectomy, radiotherapy). Inertia of the thyrotroph after thyroid hormone therapy withdrawal or long-lasting hyperthyroidism is rare and transient. Central hypothyroidism may also be idiopathic. Hypothalamic causes include: craniopharyngiomas, suprasellar extension of pituitary tumors, meningiomas, gliomas or metastatic tumors, ischemic necrosis, tuberculosis, sarcoidosis, histiocytosis X, hemochromatosis, and post-traumatic and ischemic mechanims. |
