What is human growth hormone (hGH), and how can it be used?
The pituitary gland releases a natural hormone called human growth hormone (also known as hGH or somatotropin). It acts on many body parts to promote growth, including the brain. Although hGH stops increasing height once the growth plates (epiphyses), in your bones have fused, your body still requires hGH. Once you have stopped growing, hGH is still needed to maintain normal body structure, metabolism, and blood sugar levels.
Hormones are chemicals which coordinate various functions within your body. They carry messages through your blood to your tissues, organs and muscles. These signals inform your body what to do, and when. There are over 50 hormones in your body. Many of these hormones interact with one another, creating a complicated web of processes.
The pituitary is a tiny, pea-sized endocrine organ located below your hypothalamus at the base your brain. It consists of two lobes, the anterior (frontal) and posterior (backal) lobes. The anterior lobe produces hGH.
Through a stalk of blood vessels, nerves, your pituitary gland connects to your hypothalamus. This stalk is known as the pituitary. Your hypothalamus controls functions such as blood pressure, heart beat, temperature, and digestion. Your hypothalamus communicates via the stalk with your pituitary and commands it to release certain hormones. Your hypothalamus releases the growth hormone-releasing hormone GHRH, which stimulates your pituitary to release hGH and somatostatin. This inhibits or prevents that release.
To treat certain conditions such as growth hormone deficiency, healthcare providers may use synthetic hGH (sometimes called “recombinant” hGH). A prescription from your doctor is required before you can take synthetic hGH.
What is the trigger for human growth hormone (hGH).
The pituitary gland releases hGH in short bursts throughout the day. Two hormones that your hypothalamus releases control the release of hGH: growth hormone-releasinghormone (GHRH), which stimulates the release of hGH, and somatostatin which inhibits (prevents) hGH from being released.
Other endocrine hormones, such as insulin-like growth factors 1 (IGF-1), also regulate hGH. IGF-1 is a significant suppressor of GH, while thyroxine and glucocorticoids stimulate GH release.
One of the most well-studied effects of hGH activity is IGF-1, which is released by your liver. The IGF-1 role is critical in preventing or inhibiting the release of hGH via a negative feedback loop, stimulating somatostatin release and inhibiting GHRH. IGF-1 and hGH secretion are controlled by each other. In a feedback loop, IGF-1 inhibits the release of hGH while hGH triggers IGF-1. Healthy people have a lower level of hGH than those with hyperglycemia, which is high blood sugar. They are stimulated by exercise, sleep, stress, and amino acids.
What does human growth hormone (hGH), do?
The main function of human growth hormone is to stimulate growth, mainly in children, and to impact metabolism (how your body converts food into energy).
Growth and hGH
The human growth hormone stimulates growth in almost every tissue and organ of the body. It is most famous for its growth-promoting effects on cartilage, bone, and other tissues, particularly in the adolescent years of puberty. Chondrocytes, which are cells found in cartilage, and osteoblasts (bone cells) receive signals from the hGH to increase their replication and allow growth.
After the bones of a child have fused, height is no longer an issue with hGH. Instead, hGH works to preserve your body’s normal structure for the rest of your lives.
Metabolism and hGH
Metabolism is the chemical reactions that convert food into energy. Your body needs energy to function properly. Metabolism involves many complex processes.
The main effect of hGH on metabolism is to increase insulin-like growth factor-1 production (IGF-1) in order to improve the cell-to-cell interactions. IGF-1, a hormone that is similar to insulin, manages the effects hGH has on your body. Insulin, a vital hormone that your pancreas produces, helps to regulate blood sugar levels (glucose). IGF-1, like insulin, has glucose-lowering properties.
Normal blood glucose levels are controlled by your body. Your blood glucose (or sugar) is the main sugar in your body. The carbohydrates in your food provide glucose. This sugar is an important source for energy and nutrients that feed your body’s muscles, organs, and nervous system.
Your pancreas produces insulin to lower blood glucose levels if they are too high. Glucagon is the hormone that your pancreas uses to increase glucose levels if they become too low. Epinephrine (adrenaline), and cortisol can counteract insulin’s effects.
Although hGH is known to increase blood glucose levels when they are too low, excess hGH can cause elevated blood glucose levels.
Can hGH make you taller?
Vertical growth is increased by human growth hormone in children. Once your growth plates are fused, however, hGH can’t make you taller. Instead, once you have reached your final height, the hGH will help maintain your body’s structure, and also has important effects on your metabolism.
What is the normal level of human growth hormone (hGH).
The pituitary gland releases high-quality hormones in pulses. Your age, gender, and the length of your pulses will affect how large and long they are. Healthcare providers are not able to confirm or rule out a diagnosis by using random hGH measurements. Instead, hGH measurement tests can be most useful when used in conjunction with a stimulation or suppression test.
The normal range of hGh levels is:
* Adults born to male parents: 0.4-10 nanograms per liter (ng/mL) or 18-44 picomoles/liter (pmol/L).
* Adults born to a female are assigned 1-14 ng/mL or 44-616 pmol/L
* Children: 10-50 ng/mL or 440-2200 pmol/L
The normal value ranges of different labs can vary. When analyzing your results, be sure to refer to your lab’s normal range in your lab report. Talk to your healthcare provider if you have questions about your results.
What happens if the levels of human growth hormone (hGH), are too low?
Growth hormone deficiency is a condition where you have lower levels of hGH than normal. Hypopituitarism is when your pituitary hormone gland suffers from damage or an issue. One of the affected hormones could be human growth hormone.
Adults and children are affected differently by growth hormone deficiencies.
Adults with low hGH levels
The following problems can be caused by a deficiency in hGH:
• A decreased sense of well-being
* Increased body weight
* Higher risk of developing heart disease.
* Weak heart, muscles, and bones.
Hypopituitarism in adults can be caused by a benign pituitary tumor (a non-cancerous tumor), or damage to the hypothalamus or pituitary gland.
Children with low hGH levels
Children with low levels of hGH will experience poor growth. Children who lack hGH are likely to experience slow growth in height each year after their third birthday. They will grow less than 1.4 inches per year. Also, a child who is deficient in hGH may have:
* A more youthful-looking face than is normal for their age.
* Impaired hair growth.
* Delay puberty
Hypopituitarism in children can result in hypohGH deficiency. This could be caused by hypopituitarism (idiopathic), genetic, or because of injury to the pituitary gland (during pregnancy or at birth).
Hypopituitarism can also be caused by damage to the hypothalamus or pituitary gland later in life.
What happens if the levels of human growth hormone (hGH), are too high?
Acromegaly is the main reason for higher than normal hGH levels. However, it can affect both children and adults differently. It is a rare condition.
Acromegaly in Adults
Acromegaly is a condition in which adults have swelling or swollen hands, feet, and altered facial features.
Acromegaly in adults can cause thickened bones and enlarged bodies. They are also more likely to suffer from conditions like hypertension, Type 2 diabetes, and heart disease. Pituitary adenomas (noncancerous benign) tumors on the pituitary gland account for more than 99% of all cases. These tumors can cause excess hGH. Acromegaly occurs after the end of middle-age, when all growth has stopped. Acromegaly is a condition that makes adults who aren’t taller not grow. Their bones may become thicker instead.
Acromegaly in children
Children can have elevated levels of growth hormones before reaching their final height. This can cause excessive growth of tall bones and long bones. Pediatric acromegaly is also known as gigantism. Children with acromegaly can grow up to seven feet tall if they aren’t treated. Acromegaly can also cause general weakness, delayed puberty, and headaches in children.
Pediatric acromegaly is usually caused by pituitary tumors.
What tests measure hGH levels
If you have symptoms that may be related to hGH, your healthcare provider will order a series blood tests.
The pituitary gland releases hGH in pulses throughout the day, night, and at night. Peaks occur most during the night. It is therefore difficult to interpret a single blood test to determine hGH levels and it is usually not of medical value.
Most providers use growth hormone suppression and stimulation tests to diagnose conditions resulting from excess or deficiency of hGH.
A blood test to determine the level of insulin-like growth factors 1 (IGF-1) in your blood may be ordered by them.
The U.S. Food and Drug Administration has approved the use of synthetic hGH in certain conditions. The synthetic form is only available by prescription and can be injected.
Healthcare providers recommend hGH for children to treat:
Providers prescribe hGH for adults to treat:
* Growth hormone deficiency.
* HIV infection can cause muscle tissue loss.
* Short bowel syndrome.
You should only use synthetic hGH when your doctor has recommended it.
What side effects can synthetic hGH have?
Side effects of using synthetic hGH to treat medical conditions can include:
* Carpal tunnel syndrome.
* Type 2 and/or insulin resistance increases
* Severe swelling in the legs and arms (edema).
* Muscle and joint pain.
* An increase in breast tissue (gynecomastia), in male-assigned babies.
* Higher risk of certain types of cancers
Researchers don’t have sufficient information on the long-term effects hGH treatment has on patients.
What time should I visit my healthcare provider to discuss my hGH levels and my treatment options?
Contact your healthcare provider if you or your child experience symptoms due to excess or deficiency of hGH.
Regular visits to your doctor are important if you have hGH abnormalities.
Note from Cleveland Clinic
The powerful hormone human growth hormone (hGH), is essential for many bodily functions. Sometimes your pituitary gland may produce too much or not enough of hGH. Talk to your healthcare provider if you or your child experience symptoms of hGH excess or deficiency. They are available to assist.
