What Is Growth Hormone Deficiency?
Bloodstream carries some messages from one cell to another cell in the form of chemicals. These chemical messengers are known as hormones. Growth hormones are protein hormones composed of nearly 190 amino acids which are generated and secreted by specialized cells located in the anterior pituitary known as somatotrophs, hence growth hormones are also known as somatotropin. These hormones play a role in the growth of tissues, organs and bones either indirectly or directly. In addition to regulation of composite physiologic processes, these hormones are regarded as drugs in both animals and humans.
Also See: Stress Hormones
Norms – What Is Standard Growth?
While rate of growth varies depending upon different parameters, some of these can be used to define normalcy – standard growth rate which is as listed below:
Nearly 10 inches in a year
1-2 years(12 months – 24 months)
Nearly 5 inches in a year
2-3 years(24 months – 36 months)
Nearly 3 ½ inches in a year
3 years up till puberty
Nearly 2 to 2 ½ inches a year
Lack Of Growth Hormone – When Does Deficiency In Growth Hormones Occur?
Pituitary gland is a tiny pea sized gland situated at the base of the brain. Insufficiency or deficiency in the growth hormones takes place when this gland fails to synthesize enough growth hormones. Whenever there is any damage to the pituitary gland or hypothalamus as a result of a tumor or issues with supply of blood to pituitary glands, there is a lack in the production of growth hormones.
Hypothalamus regulates hormone level in blood by stimulating the gland to produce the required quantity of hormones. Deficiency in the production of growth hormones can be as a result of issues with the pituitary gland, hypothalamus or due to the correlation between pituitary and hypothalamus. A child is said to be growth hormone deficient when a child’s growth hormone level is alarmingly low or not found at all. Inadequate levels of growth hormone production causes a child to be called growth hormone insufficient.
Growth hormone deficient children appear very short maintaining normal proportions of the body exhibiting normalcy in intelligence and appearance.
What Causes Growth Hormone Deficiency?
Broadly, causes for growth hormone deficiency can be categorized into –
Congenital causes can be as a result of damage to the hypothalamus or the pituitary gland due to an abnormality while the foetus was taking shape to be formed. Congenital growth hormone deficiency can take place if there are genetic mutations for aspects crucial in pituitary gland development or in the factors of receptors.
On the other hand, acquired cause of growth hormone deficiency can be:
- head injury/trauma
- a brain tumor in the pituitary or hypothalamus
- If treatment covers pituitary or hypothalamus, then radiation therapy for cancers can also be a cause
- lymphocytic hypophysitis – an autoimmune condition
- Diseases such as histiocytosis which infiltrate hypothalamus or its correlation to the pituitary gland
Some other reasons leading to growth hormone deficiency are:
- increased cardiovascular risk factors
- decreased bone mineral density
- decreased energy level
What Are The Symptoms Of Growth Hormone Deficiency?
It can be challenging to find the symptoms of growth hormone deficiency as growth is a natural and gradual process extending over years at different rates. However, there are few changes that can be noted alongside slow growth with normal body proportions, such as:
- Body build is healthy/chubby
- Distinguished forehead
- Appearance, in comparison to peers, is immature
- Bridge of the nose is underdeveloped
- Child’s intelligence is unaffected by deficiency in growth hormone
Above-mentioned symptoms can be similar to symptoms of other conditions, consult a physician for a proper diagnosis. This brings us to the next topic of discussion.
How Is Growth Hormone Deficiency Diagnosed?
A simple blood test can be used to diagnose growth hormone(GH). But to test for Growth hormone deficiency, a mere blood test does not fetch results as levels or hormones remain undetectable on most days, hence it is baseless to use just a sample of blood to test for GH deficiency, but multiple samples of blood are used. A combination of direct and indirect parameters is used to assess and identify the condition which include the following:
- Indirect hormonal criteria – levels of IGF from a single blood sample
- Auxologic criteria – body measurements is used as the defining factor
- Corroborative evidence of pituitary dysfunction
- GH treatment responsiveness
- Direct hormonal criteria – multiple samples of blood for measuring growth hormone in order to identity response to the provocative testing, precisely:
- Subnormal GH secretion in response to at least two provocative stimuli
- When sampled over few hours, the subnormal frequency and amplitude of GH secretory peaks
- Increased IGF1 levels after a few days of GH treatment
Adults and children, both can be diagnosed with GH deficiency. The tests for diagnosis remain the same irrespective of the age. Typically, diagnosis begins with a physical assessment where the doctor examines for signs of slow, immature growth. After this, the doctor notes body proportions, height and weight, especially when it comes to the diagnosis of children.
The blood tests for Growth Hormone Deficiency are:
- GHRH-arginine test
- Blood test to
- Measure growth hormone levels
- Measure hormone levels pituitary gland produces
- Test to determine if growth issues arises from pituitary gland – Binding protein levels (IGF-I and IGFBP-3) blood test
- Insulin tolerance test
- Growth hormone stimulation test
Some other tests for Diagnosis Of Growth Hormone Deficiency
- Measure bone density with a dual-energy x-ray absorptiometry (DXA) scan
- MRI scan to examine hypothalamus and pituitary gland
- X-ray of the hand to check size and shapes of bones
- X-ray of head, to examine bone growth of the skull
Growth Hormone Deficiency Treatment
Treatment of children and adults for growth hormone deficiency can be studied separately. Typically, the deficiency of growth hormones is treated by substituting growth hormones with injections on a daily basis that are administered into the muscle or the skin. A recombinant form of human GH, the rHGH or recombinant human growth hormone is synthesized through genetic engineering which is used.
Growth hormone therapy is the most widely and commonly used treatment in both adults and children as discussed wherein the body is injected with growth hormones. The hormone simulates the function of the actual hormone which is to trigger growth process and reproduction of cells in the body.
Daily doses of growth hormone is given, this however depends upon the severity of condition which again varies. Typically, one needs to visit the doctor every 1-2 months all through the treatment for the condition to be monitored for its progress and blood tests to be performed to decide if more GH is required.
In addition, periodic examination of cholesterol levels, bone density, blood glucose levels will also take place during the ongoing therapy. Growth hormone administration also influences the response of the body to insulin, which is pivotal in regulating the blood glucose levels.
If left untreated, growth hormone deficiency can result in high levels of cholesterol and even lead to osteoporosis.
In the first year of this treatment, children who are administered with these injections usually grow around 4 inches or more. In the span of the next 2 years, they can grow upto three inches or more. Once this feat is achieved, the growth rate begins to gradually slow down.
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