Central hypothyroidism.

Central hypothyroidism (CH) is a rare cause of hypothyroidism due to an insufficient stimulation of an otherwise normal thyroid gland and it is caused by either pituitary (secondary hypothyroidism) or hypothalamic (tertiary hypothyroidism) defects. The diagnosis of CH is usually suggested by the finding of lowered thyroid hormone concentrations, associated with inappropriately low/ normal TSH levels. Restoration and maintenance of euthyroidism represent the therapeutic goals in all forms of CH. On these basis, the vast majority of patients with CH is treated with standard levo-thyroxine (L-T4) therapy which is tailored according to FT4 circulating levels that should be maintained in the normal range.