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The growth hormone, also called the somatotropin, is a protein hormone secreted by the pituitary gland located in the brain. Its main purpose is to stimulate the cell growth and reproduction.

The medical condition in which the pituitary gland doesn’t produce enough of the growth hormone is called human growth hormone deficiency.
The good thing about this hormone is that it can now be produced synthetically and given to both children and adults for a variety of reasons but in the past, the growth hormone was extracted from human pituitary glands.

Control of growth

Most of the people don’t know that it’s not only the human growth hormone but also a few other hormones that are involved in growth regulation. Some affect the target organs directly, while others act by triggering the production of other hormones. In this chain of reactions and control, the pituitary gland is often called the master gland because it produces several hormones that control the functions of other glands.

The growth hormone is an anterior pituitary hormone whose main effect is to induce the growth of body tissues. Other anterior pituitary hormones affect growth indirectly by working through other glands. These other hormones that have something to do with the growth include:

    * Thyroid Stimulating Hormone – It causes the thyroid gland to produce the thyroid hormone, which regulates body metabolism and is essential for normal growth.
    * Adrenocorticotropic Hormone – It causes the adrenal glands to produce cortisol which enables the body to respond to stress. Too much cortisol may cause growth failure in a child.
    * Luteinizing Hormone and Follicle Stimulating Hormone – It cause the sex glands to produce sex hormones, which are necessary for adolescent sexual development and the growth that accompanies puberty.

Possible causes of growth hormone deficiency

Growth hormone deficiency may occur by itself or in a combination with one or more of the other pituitary hormone deficiencies. It may be

    * Total - when no growth hormone is produced or
    * Partial - when some growth hormone is produced, but not enough to support normal growth

There are many possible causes and some of the most common are:

  • mutations of specific genes,                                     
  • congenital malformations involving the pituitary,
  • damage to the pituitary from intracranial disease,
  • intracranial tumors in or near the sella turcica, localization place of pituitary gland,
  • damage to the pituitary from radiation therapy to the head,
  • surgery in the area of the pituitary,
  • autoimmune inflammation,
  • severe head trauma,
  • ischemic or hemorrhagic infarction from low blood pressure,
  • hemorrhage - pituitary apoplexy

The fact is that, sometimes, no cause for the deficiency can be identified or the suspected cause may be very difficult to prove.

Signs and symptoms of growth hormone deficiency

Because this hormone is affecting literally every tissue and cell in our body, there are many possible symptoms that occur when there isn't enough of the growth hormone in the blood circulation.

Some of the most common are:

    * weakened heart muscle contraction and heart rate
    * increased arterial plaque and blood pressure
    * elevated lipids or fats in the blood:
          o cholesterol
          o low density lipoproteins (LDL)                                                                                                                       
          o triglycerides
    * decreased exercise capacity due to decreased cardiac output
    * decreased energy due to decreased metabolic rate
    * abnormal body composition:
          o increased abdominal obesity (waist to hip ratio)
          o decreased bone density due to decreased synthesis of bone
          o increase in fractures and osteoporosis
          o decreased muscle strength and muscle size
          o decreased lean body mass
          o increased fat mass
    * problems with sleep quality
    * decreased social contact
    * symptoms of low blood sugar:
          o weakness or tiredness
          o headaches
          o poor concentration or memory

Diagnosis of Growth Hormone deficiency

Every hormone deficiency should be diagnosed by an internist or pediatric endocrinologists. There are several problems which may occur when an endocrinologist tries to determine if the person has some hormonal disorder. Although growth hormone can be measured in a blood sample, testing for this hormone deficiency is constrained by the fact that even the normal levels are nearly undetectable for most of the day. This is a big problem and makes the simple measurement of GH in a single blood sample useless for detecting the deficiency. And so, there are several other criteria that endocrinologists use in order to find the right diagnosis. Some of these criteria are:

    * Auxologic criteria, which is usually defined by body measurements

The child with growth hormone deficiency is often small, with an immature face and chubby body build.  The child may be much shorter than other children of the same age.

    * Direct hormonal criteria, which is based on measuring the growth hormone in multiple blood samples to determine the patterns of secreting. It is done by hospitalizing the child and measuring the amount of growth hormone present in the blood samples obtained overnight during the sleep or even during an entire 24 hour period.
    * Response to GH treatment
    * Corroborative evidence of pituitary dysfunction

Clinical characteristics of the severe GH deficiency in childhood:

  • Proportional stature well below that expected for family heights
  • Below-normal velocity of growth
  • Delayed physical maturation
  • Delayed bone age
  • Low levels of IGF1, IGF2, IGF binding protein 3
  • Subnormal frequency and amplitude of GH secreting peaks when sampled over several hours
  • Subnormal GH secretion in response to at least two provocative stimuli
  • Increased IGF1 levels after a few days of GH treatment
  • Increased growth velocity after a few months of GH treatment

Clinical characteristics of severe GH deficiency in adults

  • Body composition has higher amount of body fat
  • Subnormal bone density
  • Diminished muscle strength
  • Higher cholesterol levels
  • Low IGF1 level
  • Subnormal frequency and amplitude of GH secreting peaks when tracked over several hours
  • Subnormal GH secretion in response to at least two provocative stimuli
  • Increased IGF1 levels after a few days of GH treatment

Treatment of Growth hormone deficiency

The only way to treat the Growth hormone deficiency is with the growth hormone injections . The fact is that all GH prescribed in North America, Europe, and most parts of the rest of the world is a synthetic form of human GH, manufactured by recombinant DNA technology. Because human growth hormone is a very large molecule, it must be injected into subcutaneous tissue or muscle to get it into the blood. The good side of this treatment is that, when a person has had a long-standing deficiency of GH, benefits of the treatment are often obvious, and side effects of the treatment are rare.

Treatment of GH deficiency in children

Biosynthetic growth hormone is supplied as a powder in sterile vials. Parents and children are taught how to mix the powder into a solution and administer the injections. Children are treated with GH injections and while some children receive three of four injections a week, other receive them daily. There is usually a prompt increase in growth rate after the treatment starts, which may be noticeable to both the child and the parents in 3 to 4 months. This slowly declines over time. GH promotes the growth of the muscles and bones in children, while the shift of lipid metabolism tends to be work in the opposite direction. about the bad side of this treatment is that it involves daily injections of growth hormone, usually for as long as the child is growing. A small percentage of children receiving GH develop a low level of weak antibodies to the medication. Another problem with this therapy are the costs. The growth hormone therapy is one of the most expensive treatments in all of medicine. The treatment costs vary depending on the country and on the size of the child, but $US 10,000 to 30,000 a year is the average. The highest cost, for Treating the severe, congenital GH deficiency from infancy to the age of 70 may cist more than US$300,000.
Good nutrition and adequate rest are important for normal growth in all children. However the prognosis is very good!
With an early diagnosis and a good response to treatment, children with growth hormone deficiency can expect to reach normal adult height.

Growth hormone is also approved for

  • Children with short stature
  • Children with kidney disease
  • Children with Prader-Willi syndrome
  • Children with Turner's syndrome
  • Muscle wasting associated with AIDS and HIV

Treatment of adult GH deficiency

Research has shown that GH treatment can provide a number of measurable benefits to the adults who are suffering from the growth hormone deficiency. Some of the beneficial effects are

  • Enhanced energy and strength
  • Improved bone density
  • Muscle mass may increase at the expense of adipose tissue
  • Blood lipid levels improve

Severe adult growth hormone deficiency is usually treated by daily injections with a weekly dose of about 25% of children's doses. It is logical to assume that this is done at a comparably lower cost.

Read More: Human Growth Hormone (HGH) Side Effects

Risks of hormone replacement therapy

The good thing about this treatment is that there are not so many possible side effects that could occur but, among those that can occur, the most common are:

  • Slipped capital femoral epiphysis
  • Pseudotumor cerebri, also known as benign intracranial hypertension
  • Fluid retention and edema
  • Pancreatitis
  • Joint pains
  • Carpal tunnel syndrome
  • Insulin sensitivity
  • Type 2 diabetes
  • Leukemia
  • Colon cancer
  • Headaches
  • Bloating
  • Muscle pain
  • Abnormal growth of bones and internal organs
  • Hardening of the arteries
  • High blood pressure