Hyperpituitarism
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Hyperpituitarism is a condition due to the primary hypersecretion of pituitary hormones; it typically results from a
pituitary adenoma Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas.


Symptoms and signs

Symptoms caused by hormone excess and associated mass effects include:


Cause

The cause of hyperpituitarism in most cases is due to pituitary adenomas. They usually come from the anterior lobe, are functional and secrete the hormone, GH and prolactin.


Mechanism

Evidence indicates that the mechanism of hyperpituitarism can originate from genetic disruption causing pituitary tumorigenesis, most pituitary adenomas are monoclonal, which in turn indicates their origin from an event in a single cell. There are three hormones that are oversecreted resulting in the pituitary adenoma:
prolactin Prolactin (PRL), also known as lactotropin and mammotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secr ...
,
adrenocorticotropic hormone Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important ...
(ACTH), and
growth hormone Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in ...
(GH). Excess prolactin may result in a
prolactinoma A prolactinoma is a tumor (adenoma) of the pituitary gland that produces the hormone prolactin. It is the most common type of functioning pituitary tumor. Symptoms of prolactinoma are due to abnormally high levels of prolactin in the blood ( hyp ...
Excess GH results in
gigantism Gigantism (, ''gígas'', "wiktionary:giant, giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average height, average. In humans, this conditi ...
, the severity of gigantism depends on whether the
epiphyseal plate The epiphyseal plate, epiphysial plate, physis, or growth plate is a hyaline cartilage plate in the metaphysis at each end of a long bone. It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, with ma ...
is open. The four most common types of hyperpituitarism are caused by 4 types of pituitary adenoma, as follows: prolactinoma, corticotropinoma (
Cushing's disease Cushing's disease is one cause of Cushing's syndrome characterised by increased secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary (secondary hypercortisolism). This is most often as a result of a pituitary adenoma (spec ...
), somatotropinoma (gigantism), and thyrotropinoma .


Diagnosis

For the diagnosis of hyperpituitarism it depends on the cell type(s) affected, clinical manifestations of hormone excess may include,
gigantism Gigantism (, ''gígas'', "wiktionary:giant, giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average height, average. In humans, this conditi ...
or
acromegaly Acromegaly is a disorder that results in excess growth of certain parts of the human body. It is caused by excess growth hormone (GH) after the growth plates have closed. The initial symptom is typically enlargement of the hands and feet. There ...
, which can be identified by clinical and radiographic results. Cushing's disease diagnosis is done with a physical examination, laboratory tests and MRI of the pituitary gland (to locate tumors) For prolactinoma, diagnosis comes in the form of the measurement of serum prolactin levels and MRI of pituitary gland.


Treatment

Treatment (for hyperpituitarism) in the case of prolactinoma consists of long-term medical management.
Dopamine Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic chemical of the catecholamine and phenethylamine families. It is an amine synthesized ...
agonists are strong suppressors of PRL secretion and establish normal gonadal function. It also inhibits tumor cell replication (in some cases causes tumor shrinkage) Treatment for gigantism begins with establishing target goals for IGF-1, transsphenoidal surgery (somatostatin receptor ligands- preoperatively) and postoperative imaging assessment. For Cushing's disease there is surgery to extract the tumor; after surgery, the gland may slowly start to work again, though not always.


See also

* Hypopituitarism


References


Further reading

* * *


External links

{{Pituitary disease Pituitary disorders