[Inadequate TSH secretion. Clinical features, diagnostic criteria, and therapeutic possibilities].

Inadequate secretion of TSH (IST) is a disorder which is diagnosed more frequently and earlier after the introduction of new immunoassay techniques which can distinguish between normal and suppressed TSH levels. For diagnosis high or unsuppressed TSH in required in the presence of elevated levels of the thyroid hormones. Its etiology may be tumor (TSH secreting pituitary adenoma) or non tumoral due to pituitary or generalized resistance to the thyroid hormones.