[Thyrotropic pituitary adenoma. Clinical aspects, course and treatment]

Thyrotropic pituitary adenoma is a rare disease fortunately diagnosed with increasing frequency. Its originality lies in the fact that it occurs in two very different pathological contexts. The first form raises few problems: the occurrence of a pituitary tumoral syndrome in a patient with hypothyroidism, even of relatively short duration, should suggest the diagnosis. In such cases of reactive thyrotropic adenoma, simple correction of the hypothyroidism by replacement therapy seems to be capable not only of curing the thyroid disorder and lowering TSH values, but also of promoting regression of the pituitary tumour. Primary autonomous adenoma responsible for TSH hypersecretion followed by thyrotoxicosis belongs to the realm of inappropriate TSH secretion, and it should be diagnosed whenever high, or even normal (at least non-suppressed). TSH levels coexist with peripheral hyperthyroidism. As a rule, the presence of a pituitary tumour differentiates this adenoma from non-tumoral inappropriate TSH secretion due to resistance to thyroid hormones. Primary thyrotropic pituitary adenoma is treated by surgery. In case of failure or relapse, radiotherapy or medical treatment with a dopaminergic agonist or a long-acting somatostatin analogue may be considered.