Growth hormone deficiency overview

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Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Growth hormone deficiency from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Criteria

History and Symptoms

Physical Examination

Laboratory Findings

X Ray

CT

MRI

Echocardiography or Ultrasound

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

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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

Growth hormone deficiency (GHD) is a rare disorder characterized by the inadequate secretion of growth hormone (GH) from the anterior pituitary gland, a small gland located at the base of the brain that is responsible for the production of several hormones. GHD can be present from birth (congenital), resulting from genetic mutations or from structural defects in the brain. It can also be acquired later in life as a result of trauma, infection, radiation therapy, or tumor growth within the brain. A third category has no known or diagnosable cause (idiopathic). Childhood-onset GHD may be all three: congenital, acquired, or idiopathic. It results in growth retardation, short stature, and maturation delays reflected by the delay of lengthening of the bones of the extremities that is inappropriate to the chronological age of the child. Adult-onset GHD is most often is acquired from a pituitary tumor or trauma to the brain but may also be idiopathic. It is characterized by a number of variable symptoms including reduced energy levels, altered body composition, osteoporosis (reduced bone mineral density), reduced muscle strength, lipid abnormalities such as increased LDL cholesterol, insulin resistance, and impaired cardiac function. Treatment for GHD requires daily injections of recombinant human growth hormone. Patients with GHD that have no known cause are diagnosed as having idiopathic GHD. Genetic tests may reveal a congenital anomaly, but are often considered unnecessary after confirmation of GHD since they will have no effect on treatment. However, it is recommended that children be retested for GHD when they transition from pediatric to adult care since GH levels may normalize upon reaching adulthood. The level of GH considered normal for an adult is much lower than that for a child, especially one undergoing the pubertal growth spurt.

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 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 POU1F1PROP-1, and GH-1 genes. Structural causes can cause growth hormone deficiency such as optic nerve hypoplasiaagenesis of corpus callosumsepto-optic dysplasiaempty 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, craniopharyngiomapituitary adenoma.

Differentiating ((Page name)) 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

Risk Factors

There are no established risk factors for growth hormone deficiency.

Screening

Natural History, Complications, and Prognosis

If left untreated, patients with growth hormone deficiency may progress to develop delayed postnatal growthdelayed bone agedelayed puberty, infantile fat distribution, and infantile voice. Common complications of growth hormone deficiency include osteopeniadyslipidemiadelayed 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

Diagnostic Criteria

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 asphyxiahypoglycemia, 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

Electrocardiogram

X-ray

CT scan

Pituitary CT scan may be helpful in the diagnosis of growth hormone deficiency if an MRI is not available.

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 headachesIdiopathic intracranial hypertensionSlipped capital femoral epiphysis, worsening of existing scoliosisPancreatitis, 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

Secondary Prevention

References


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