Growth hormone deficiency overview
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Differentiating Growth hormone deficiency from other Diseases |
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Diagnosis |
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Treatment |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D[2]
Overview
Historical Perspective
In the mid-1940s, bovine GH has been purified for the first time then, growth hormone was isolated from the human pituitary gland in 1956. 7700 children in the United States and 27,000 children worldwide were given GH extracted from human pituitary glands. In 1981, Genentech developed the first recombinant human GH.
Classification
Growth hormone deficiency can be classified by nature into congenital type in which infants show symptoms such as hypoglycemia, neonatal growth failure, neonatal jaundice, and asphyxia or acquired type presents with severe growth failure, delayed bone age, delayed puberty.
Pathophysiology
The somatotroph cells of the anterior pituitary gland produce growth hormone. GH best-known effect is increasing body mass. GH causes epiphyseal plate widening and cartilage growth. GH deficiency results in alterations in the physiology of different systems of the body, manifesting as altered lipid metabolism, increased subcutaneous visceral fat, decreased muscle mass. Genetic basis of congenital growth hormone deficiency depends on many genes, for example, POU1F1 gene mutations are the most common known genetic cause of the combined pituitary hormone deficiency. Gene deletions, frameshift mutations, and nonsense mutations of GH1 gene have been described as causes of familial GHD.
Causes
Causes of growth hormone deficiency could be congenital or acquired. Congenital causes include genetic mutations in POU1F1, PROP-1, and GH-1 genes. Structural causes can cause growth hormone deficiency such as optic nerve hypoplasia, agenesis of corpus callosum, septo-optic dysplasia, empty sella syndrome, and holoprosencephaly. Acquired causes can cause growth hormone deficiency such as GHD following brain surgery and radiation therapy for brain tumors, central nervous system infection, craniopharyngioma, pituitary adenoma.
Differentiating growth hormone deficiency from Other Diseases
Growth hormone deficiency in children must be differentiated from other diseases that cause short stature in children such as achondroplasia, constitutional growth delay, familial short stature, growth hormone resistance, Noonan Syndrome, panhypopituitarism, pediatric hypothyroidism, psychosocial short stature, short stature accompanying systemic disease, short stature from abuse and neglect, Silver-Russell Syndrome, and Turner Syndrome.
Epidemiology and Demographics
If left untreated, patients with growth hormone deficiency may progress to develop delayed postnatal growth, delayed bone age, delayed puberty, infantile fat distribution, and infantile voice. Common complications of growth hormone deficiency include osteopenia, dyslipidemia, delayed puberty, and higher mortality rates than normal subjects. Prognosis is generally good with treatment. GH treatment can improve GH-deficient adults symptoms. Since recombinant DNA–derived growth hormone became available, most children with growth hormone deficiency reach normal adult stature.
Risk Factors
There are no established risk factors for growth hormone deficiency.
Screening
Genetic screening of growth hormone deficiency is indicated for patients with early and severe symptoms. GHD patients have been screened for mutations in the GH1 and GHRH gene. Understanding of genetic contributions to GHD opens the possibility for a more rational approach to the diagnosis and management of GHD.
Natural History, Complications, and Prognosis
If left untreated, patients with growth hormone deficiency may progress to develop delayed postnatal growth, delayed bone age, delayed puberty, infantile fat distribution, and infantile voice. Common complications of growth hormone deficiency include osteopenia, dyslipidemia, delayed puberty, and higher mortality rates than normal subjects. Prognosis is generally good with treatment. GH treatment can improve GH-deficient adults symptoms. Since recombinant DNA–derived growth hormone became available, most children with growth hormone deficiency reach normal adult stature.
Diagnosis
History and Symptoms
The hallmark of growth hormone deficiency is growth failure. The most common symptoms of GHD in infants are delayed Bone age, perinatal asphyxia, hypoglycemia, and jaundice. Adults symptoms include increased lean body mass, fractures of the lumbar spine, and osteopenia.
Physical Examination
Patients with growth hormone deficiency usually look tired and less energetic than normal subjects. Extremities show Clubbing, muscle atrophy, neonatal jaundice, neonatal cyanosis. Head may show infantile facies, delayed dentition, and brittle hair. Children may show hyporeflexia and delayed puberty.
Laboratory Findings
An immediate investigation should be started in severe short stature defined as a short child more than 3 sd below the mean of children at the same age. Measurement of a random serum GH level alone is not helpful. Measurement of Insulin-like growth factor I (IGF-I) and Insulin-like growth factor binding protein-3 (IGFBP-3) is more helpful than GH level alone.
GH stimulation tests is indicated for most patients suspected to have GHD. If the clinical and other laboratory criteria are sufficient to make the diagnosis of GHD, there is no need to perform the test. Pharmacologic stimuli include clonidine, glucagon, arginine, and insulin-induced hypoglycemia. Administration of sex steroids for a few days prior to the provocative GHtesting reduces the chance of a false-positive result.
Electrocardiogram
X-ray
An x-ray may be helpful in the diagnosis of delayed bone age associated with growth hormone deficiency.
CT scan
Pituitary CT scan may be helpful in the diagnosis of growth hormone deficiency if an MRI is not available.
MRI
Brain MRI may be helpful in the diagnosis of growth hormone deficiency. On T1-weighted imaging, a clear demarcation can be made between the adenohypophysis and the neurohypophysis, which appears as hyperintense. Other pituitary abnormalities such as anterior pituitary hypoplasia, pituitary stalk agenesis, and posterior pituitary ectopia can be diagnosed using MRI.
Ultrasound
There are no ultrasound findings associated with growth hormone deficiency.
Other Imaging Findings
There are no other imaging findings associated with growth hormone deficiency.
Other Diagnostic Studies
There are no other diagnostic studies associated with growth hormone deficiency.
Treatment
Medical Therapy
Growth hormone (GH) is indicated for children with GH deficiency whose epiphyses are open. The dose for children is between 0.16 and 0.24 mg/kg/week, divided into once daily injections. Serum levels of insulin-like growth factor I (IGF-I) should be measured several weeks after beginning GH treatment or making a dose adjustment. GH side effects include headaches, Idiopathic intracranial hypertension, Slipped capital femoral epiphysis, worsening of existing scoliosis, Pancreatitis, and Gynecomastia. There is a possible role for GH in cancer risk.
Surgery
Surgical intervention is not recommended for the management of growth hormone deficiency.
Primary Prevention
There are no established measures for the primary prevention of growth hormone deficiency.