Growth Hormone Deficiency in Adults

Updated: Nov 07, 2017
  • Author: Mohsen S Eledrisi, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Overview

Practice Essentials

The somatotroph cells of the anterior pituitary gland produce growth hormone (GH), which is stimulated by GH-releasing hormone (GHRH) and inhibited by somatostatin, both of which are produced by the hypothalamus.

GH deficiency in adults usually manifests as reduced physical performance and impaired psychological well-being. It results in alterations in the physiology of different systems of the body, manifesting as altered lipid metabolism, increased subcutaneous visceral fat, decreased muscle mass, decreased bone density, low exercise performance, and reduced quality of life. [1]

Adult GH deficiency can be a transition from childhood-onset GH deficiency or can be acquired during adulthood. The majority of cases are caused by pituitary tumors or by their treatment with surgery, radiation therapy, or both. Traumatic brain injury is another important cause.

The goals of GH therapy in adults are to improve conditioning and strength, improve quality of life, and decrease the burden of associated medical conditions such as cardiovascular disease and reduced bone mineral density.

Patients should be educated about the technique of subcutaneous injection of GH.

For excellent patient education resources, visit eMedicineHealth's Thyroid and Metabolism Center. Also, see eMedicineHealth's patient education articles Growth Hormone DeficiencyGrowth Hormone Deficiency Medications, and Growth Hormone Deficiency FAQs.

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Pathophysiology

 

 

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Epidemiology

An estimated 6,000 adults are diagnosed with GH deficiency every year in the United States. [2] Adult GH deficiency has been estimated to affect 1 in 100,000 people annually, while its incidence is approximately 2 cases per 100,000 population when childhood-onset GH deficiency patients are considered. About 15-20% of the cases represent the transition of childhood GH deficiency into adulthood. [3]

The age of presentation of acquired GH deficiency in adults often coincides with the discovery of pituitary tumors, usually between the fourth and fifth decades of life.

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Etiology

The main cause of GH deficiency is a pituitary tumor or the consequences of treatment of the tumor, including surgery and/or radiation therapy. Traumatic brain injury is increasingly being recognized as an important cause of GH deficiency, both during the acute stage of injury and during the rehabilitation stage (5,6). [4, 5]

Causes of GH deficiency can be divided into 3 categories: congenital, acquired, and idiopathic (4).

Congenital conditions are caused by genetic abnormalities or structural brain defects. Genetic abnormalities include transcription factor defects (PIT-1, PROP-1, LHX3/4, HESX-1, PITX-2), GHRH receptor gene defects, GH gene defects, and GH-receptor or post-receptor defects. Structural defects include agenesis of corpus callosum, septo-optic dysplasia, empty sella syndrome, encephalocele, hydrocephalus, and arachnoid cyst. GH deficiency can occur in association with midline facial defects such as single central incisor, cleft lip, and cleft palate.

Acquired conditions of GH deficiency include tumors of the pituitary gland or the hypothalamus and metastatic disease; surgery or radiation therapy of the pituitary or hypothalamus; infiltrative diseases such as sarcoidosis, tuberculosis, histiocytosis X, hemochromatosis, and lymphocytic hypophysitis; infarction of the pituitary or hypothalamus (which can be spontaneous or result from Sheehan syndrome); and head trauma.

In some cases, no clear etiology can be determined.

 

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