Hypothyroidism hyperprolactinemia

Destruction of the pituitary gland may result in secondary hypothyroidism, hypogonadism, adrenal insufficiency, growth hormone deficiency, and hypoprolactinemia. The formation of certain types of pituitary tumors may result in pituitary hormone excess. Pituitary tumors may also physically compress the pituitary and prevent the release of the trophic hypothalamic factors that regulate pituitary hormones. In this chapter, the pathophysiology and role of pharmacotherapy in the treatment of acromegaly, short stature, hyperprolactinemia, and panhypopituitarism will be discussed. 

Less common etiologies include central nervous system lesions that physically compress the pituitary stalk and interrupt tonic hypothalamic dopamine secretion, resulting in hyperprolactinemia. Increased thyroid-releasing hormone (TRH) concentrations in hypothyroidism can stimulate prolactin secretion and cause hyperprolactinemia. During conditions of renal or liver compromise, the... 

Like other anterior pituitary hormones, prolactin is secreted in a pulsatile manner. Prolactin is unique among the anterior pituitary hormones in that hypothalamic regulation of its secretion is predominantly inhibitory. The major regulator of prolactin secretion is dopamine, which is released by tuberoinfundibular neurons and interacts with the Dj receptor on lactotropes to inhibit prolactin secretion. A number of putative prolactin-releasing factors have been described, but their physiological roles are unclear. Under certain pathophysiological conditions, such as severe primary hypothyroidism, persistently elevated levels of TRH can induce hyperprolactinemia and consequent galactorrhea. 

Prolactin has no therapeutic uses. Hyperprolactinemia is a relatively common endocrine abnormality that most often is caused by prolactin-secreting pituitary adenomas. Hyperprolactinemia also can result from hypothalamic or pituitary diseases that interfere with the delivery of inhibitory dopaminergic signals primary hypothyroidism associated with increased TRH levels renal failure treatment with dopamine receptor antagonists. Manifestations of prolactin excess in women include galactorrhea, amenorrhea, and infertihty. in men, hyperprolactinemia causes loss of libido, impotence, and infertility. 

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