What is Hyperpituitarism?
Hyperpituitarism, also called acromegaly and gigantism, is a chronic, progressive disease marked by hormonal dysfunction and startling skeletal overgrowth. The prognosis depends on the causative factor, but this disease usually reduces life expectancy.
Hyperpituitarism appears in two forms: acromegaly (rare) and gigantism. Acromegaly occurs after epiphyseal closure, causing bone thickening and transverse growth and visceromegaly. This form of hyperpituitarism occurs equally among men and women, usually between the ages of 30 and 50.
Gigantism begins before epiphyseal closure and causes proportional overgrowth of all body tissues. As the disease progresses, loss of other trophic hormones, such as thyroid-stimulating hormone, luteinizing hormone, follicle-stimulating hormone, and corticotropin, may cause dysfunction of the target organs.
Gigantism affects infants and children, causing them to grow to as much as three times the normal height for their age. As adults, they may eventually reach a height of more than 8' (2.4 m).
Causes of Hyperpituitarism
In most patients, the source of excessive growth hormone (GH) or human growth hormone secretion is a GH-producing adenoma of the anterior pituitary gland, usually macroadenoma (eosinophilic or mixed-cell). The etiology of the tumor is unclear. Occasionally, hyperpituitarism occurs in more than one family merber, suggesting a genetic cause.
Signs & Symptoms of Hyperpituitarism
Acromegaly develops slowly. In many people, the changes are so slow that they are not noticed for years. Some of the Signs and symptoms of Hyperpituitarism include:
The tests that support a diagnosis of hyperpituitarism include GH radioimmunoassay, which shows increased plasma GH levels. Because GH isn't secreted at a steady rate, a random sampling may be misleading. This test also shows increased levels of insulin-like growth factor I (somatocedin-C); these levels are a better screening alternative.
Glucose suppression test offers more reliable information. Glucose normally suppresses GH secretion; therefore, a glucose infusion that fails to suppress the hormone level to below the accepted norm of 2 ng/ml strongly suggests hyperpituitarism when combined with characteristic clinical features.
Skull X-ray, computed tomography scanning, or magnetic resonance imaging may help to locate the pituitary tumor, and bone X-rays show a thickening of the cranium (especially of frontal, occipital, and parietal bones) and of the long bones as well as osteoarthritis in the spine.
The aim of treatment is to curb overproduction of GH by removing the underlying tumor. Removal occurs by cranial or transsphenoidal hypophysectomy or pituitary radiation therapy. In acromegaly, surgery is mandatory when a tumor is compressing surrounding healthy tissue. Postoperative therapy commonly requires replacement of thyroid, cortisone, and gonadal hormones. Adjunctive treatment may include bromocriptine, which inhibits GH synthesis, and octreotide acetate, a long-acting analogue of somatostatin that suppresses GH secretion in at least two-thirds of patients with acromegaly.
No measures exist to prevent the initial condition, but early treatment may prevent any worsening of complications associated with this disease.
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