Exercise Capacity And Performance
Increased exercise capacity, as measured by maximal oxygen uptake, power output, and isometric muscle strength, has been observed during GH replacement in GH deficient adults . A meta-analysis concluded that evidence from short-term controlled studies failed to support a benefit on muscle strength of GH replacement in GH deficient patients, which is likely to occur over a longer time-course, as seen in open-label studies .
The impact of these changes for individual patients is variable and dependent on age and previous exercise requirements. It is intuitively probable that the improvements depend at least in part on improvements in lean body mass. However, restoration of normal circulating volume may also play a positive role . In addition, improvement in psychological well-being might be expected to enhance physical activity whilst the latter may have a reciprocal beneficial effect on well-being.
How Does Growth Hormone Therapy Work
It is an unfortunate fact of life, that as we age, we lose HGH and other vital hormones such as testosterone. As the levels of these critical hormones drop, all bodily processes slow down and become less efficient. Much of the symptoms we think of as aging, are really a reflection of declining levels of testosterone and HGH.
Growth hormone therapy can return your HGH to more youthful levels, which can slow, and in some cases, even reverse the debilitating effects of age related growth hormone deficiency.
As the level of HGH in your body increases, your ability to repair and replace old and dying cells increases. Your liver is stimulated to release more IGF, which gives cellular metabolism an additional boost. These two actions combine to return your strength, energy and ability to burn fat and build muscle, to what they were when you were younger. This is how growth hormone therapy works to make you look and feel younger and stronger!
What Kind Of Results Could I Expect From Growth Hormone Therapy
If you have had your HGH levels tested, and you have received a diagnosis of adult growth hormone deficiency, you can expect to see many benefits from growth hormone therapy, such as increased muscle mass, loss of fat, and renewed energy.
For men and women who have been diagnosed with age-related GHD, growth hormone injections have been found to:
- Improve fat metabolism, resulting in lower body mass index
- Increase energy and stamina
- Improve memory and other cognitive functions
- Increase libido and improve sexual performance
- Strengthen bones, and fight osteoporosis
In addition, HGH injections can also improve heart health by helping to reduce cholesterol, and open blood vessels that have been clogged with arterial plaque.
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Diagnosis Of Gh Deficiency Without Gh Stimulation Tests
- Struttura Semplice Dipartimentale Endocrinologia Pediatrica e Centro Screening Neonatale, Ospedale Pediatrico Microcitemico A. Cao, Azienda di Rilievo Nazionale ed Alta Specializzazione G. Brotzu, Cagliari, Italy
Growth hormone deficiency is the most commonly affected pituitary hormone in childhood with a prevalence of 1 in 400010000 live births. GH stimulation testing is commonly used in the diagnostic workup of GHD. However, GHD can be diagnosed in some clinical conditions without the need of GHST. The diagnosis of GHD in newborns does not require stimulation testing. Likewise infants/children with delayed growth and/or short stature associated with neuroradiological abnormalities and one or more additional pituitary hormone deficiencies may not need GHST. This review summarizes the current evidence on the diagnosis of GHD without stimulation tests.
What Are The Different Kinds Of Growth Hormone Deficiency
There are three main types of growth hormone deficiency , including:
- Congenital GHD: Congenital GHD means its present from birth due to a genetic mutation or structural issues in the babys brain.
- Acquired GHD: GHD is considered to be acquired if its onset is later in life as a result of damage to your pituitary gland. Children and adults can have acquired GHD.
- Idiopathic GHD: In the medical world, idiopathic means theres no known cause. Some cases of GHD have an unknown cause.
Growth hormone deficiency is also categorized by the age of onset. It has different symptoms and processes for diagnosis if youre a child or adult when the condition begins.
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What Happens During The Test
For your child, the test begins with a technician placing an IV line in their arm or hand.
After giving a blood sample, your child will get a dose of medicine or medicines to stimulate the pituitary gland to release growth hormone. The most common medicines chosen are clonidine , arginine or glucagon. Insulin is less commonly used now because of safety concerns with children.
During all of this, the assistant will probably take a blood sample around every 30 minutes. The samples are not large — perhaps a couple of teaspoons, total, over the course of the day.
At the end of the test, your child can eat. They should rest afterwards.
Itâs a similar process for adults who get the GH stimulation test. Adults have the option of a medicine called macimorelin which is given as a liquid to drink. Insulin is less often used now because of unpleasant side effects and safety concerns due to low blood sugars.
Both children and adult blood samples can also be checked for IGF-1 and IGFBP-3 alongside the stimulation test.
If you take the GH suppression test, youâll drink a glucose solution in the first 5 minutes, and get your blood checked every 30 minutes for 2 hours.
Growth hormone tests arenât likely to cause any complications, though some people may feel faint. Bruising is possible where the IV line went into your vein.
Normal Growth Hormone Levels By Age
Jennifer Osipoff, MD, a pediatric endocrinologist with Stony Brook Childrens Hospital, says that growth hormone is secreted from the pituitary gland mainly during sleep. Still, this secretion also occurs in small spurts throughout the day.
As such, a random GH level is not a clinically relevant value if assessing for growth hormone deficiency or excess, Osipoff said. Instead, endocrinologists will measure insulin-like growth factor 1 , a protein that is made in response to GH secretion.
Providers break passing levels down into two groups: pediatric patients under 18 and adult patients 18 and over.
| Age |
| acromegaly | rare |
GHD is rare, and it doesnt usually explain a childs short stature or slow growth. A child may have below-average height for many reasons, including simple genetics.
Slow growth is also common for children, especially right before puberty. Children with a GH deficiency often grow under 2 inches per year.
A healthcare professional may also recommend GH testing if they notice signs a childs body is producing too much GH. For example, this can happen with a rare condition known as gigantism, which causes the long bones, muscles, and organs to grow excessively in childhood.
Adult bodies rely on GH to maintain muscle mass and bone density and regulate metabolism.
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Patients Transitioning From Pediatric To Adult Care
Laboratory retesting for GHD is also appropriate to determine if GHD is persistent in patients transitioning from pediatric to adult care who have been off GH treatment for at least 1 month with:
- Suspected hypothalamic GHD
- Idiopathic isolated GHD
- Organic GHD with deficiency of two or fewer pituitary hormones in addition to GH
Testing for GHD is also appropriate in transition patients after radiation treatment.
How Is Growth Hormone Deficiency Treated
Treatment for growth hormone deficiency in both children and adults involves synthetic growth hormone injections given at home. People with GHD most often need a daily shot.
Synthetic growth hormone treatment is long-term, often lasting for several years. Its essential to see your healthcare provider regularly to make sure the treatment is working and to see if you need to adjust your dose of medication.
If you or your child have deficiencies in other pituitary hormones, you or they will also need treatment to correct those deficiencies.
Side effects of growth hormone deficiency treatment
Mild to moderate side effects of growth hormone injections for the treatment of growth hormone deficiency are uncommon. They include:
- Mildly underactive thyroid gland .
- Swelling of your hands and feet.
- Progression of spine curvature in people with scoliosis.
Rare but serious side effects of GHD treatment include:
- Severe headache with vision problems.
- Hip dysplasia .
If youre experiencing any of these symptoms, its important to talk to your healthcare provider. They may need to adjust your medication dose.
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What Happens During A Growth Hormone Test
Your provider may order a GH stimulation or a GH suppression test, depending on whether symptoms show a possible GH deficiency or a GH excess .
A GH stimulation test is used to check for a GH deficiency. During the test:
- A health care professional will take a blood sample from a vein in your arm, using a small needle.
- After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
- Your child will be given a medicine through an IV line that stimulates the pituitary gland to make GH.
- More blood samples will be taken over the course of about two hours.
- Each sample will be tested to see if GH levels have increased.
A GH suppression test is used to check for a GH excess. During the test:
- A health care professional will take a blood sample from a vein in your arm, using a small needle.
- After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
- You or your child will drink a solution that contains water and glucose .
- Two more blood samples will be taken within one to two hours after drinking the solution.
- The blood samples will be tested to see if GH levels have decreased.
Establishing The Maintenance Gh Dose
When the indication for GH-replacement has been ascertained, the patient is usually on a low initial dose , but dependent on age, since adolescents during transition may benefit from higher initial doses, as will also women on estrogen therapy a higher dose may be employed . The dose titration is monitored by IGF-I concentrations , and a number of end organ end responses, which may act as biomarkers of the treatment effects .
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Gh Stimulation In Children
The exercise stimulation test is often used as an initial screen for GH deficiency, but combinations of other tests have been advocated by various institutions. A subnormal response from a single provocative test is not diagnostic for GH deficiency and should be confirmed with a second provocative test. These tests produce an increase in plasma GH to > 7 ng/mL in individuals with appropriate GH production.1-3 Some institutions use 10 ng/mL as a cutoff for normal GH response.1,3
The insulin-induced hypoglycemia and the GHRH tests provide additional information beyond establishing GH deficiency. The insulin-induced hypoglycemia test allows the assessment of the entire hypothalamic-pituitary-adrenal axis. A normal GH response to GHRH in a patient proven to be GH deficient by previous stimulation testing suggests that the GH deficiency is due to insufficient GHRH production by the hypothalamus.
Due to low baseline levels of GH, prepubertal children should be primed prior to performing the stimulation tests by one of the following:3
How Is Growth Hormone Deficiency In Adults Tested And Diagnosed
If you are an adult over 40, and are exhibiting any number of the above symptoms, your doctor will likely want to have you tested for a growth hormone deficiency. There are a number of ways to test for growth hormone deficiency in adults, however, they all start with drawing blood.
Since HGH levels in your blood rise and fall during the day, and vary from day to day, a test that simply measures the presence of HGH in your blood is not adequate enough to achieve a diagnosis of growth hormone deficiency. More sophisticated testing is required.
The way we test for growth hormone deficiency in adults is to use what are known as stimulation tests. Rather than testing for the presence or level of HGH in your blood at any given time, HGH stimulation tests introduce a medication that is supposed to stimulate your pituitary gland to release growth hormone. Similarly, a test that stimulates the release of another hormone, related to HGH, IGF-1, may also be used.
These growth hormone stimulation tests may be used alone or in combination. In any case, once the stimulant is introduced, your blood will be drawn and evaluated for adequate production and release of growth hormone.
Rather than testing for the presence or level of HGH in your blood at any given time, HGH stimulation tests introduce a medication that is designed to stimulate your pituitary gland to release growth hormone.
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How Doctors Interpret Test Results
As we discussed earlier, doctors rely on at least two, often more, tests to make a definitive diagnosis of GH deficiency. Several disorders, such as adrenal insufficiency, can mimic the symptoms and test results that might indicate GH. Therefore, care is required to make an accurate diagnosis.
Depending on the type of test, results can sometimes take several days to come back. Once they do, we will schedule a new consultation with you to review your results. Always keep in mind that only licensed, experienced doctors are qualified to skillfully interpret your test results. The neuroendocrine system is complex, requiring a skilled set of eyes to accurately read the results of your HGH deficiency examinations.
When Should I See My Healthcare Provider About Growth Hormone Deficiency
There are many reasons for slow growth and below-average height in children. At times, slow growth is normal and temporary, such as right before puberty starts. If youre concerned about your childs rate of growth, see a pediatric endocrinologist or healthcare provider. They can help find out if your childs rate of growth is cause for concern.
If youre an adult and are experiencing symptoms of growth hormone deficiency , talk to your healthcare provider.
If you or your child have been diagnosed with GHD, youll need to see your healthcare provider regularly to make sure your treatment is working properly.
A note from Cleveland Clinic
If youre noticing a lack of growth in your child, its important to talk to their healthcare provider as soon as possible. While it may be unlikely that growth hormone deficiency is the cause, any concerning changes are worth evaluating. People with GHD who are diagnosed early have the best outlook and usually lead healthy lives. If you have any questions about what to expect with your childs growth, dont be afraid to reach out to their provider. Theyre there to help.
Last reviewed by a Cleveland Clinic medical professional on 06/21/2022.
References
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Carbohydrate Metabolism And Insulin Sensitivity
Untreated GH deficiency of adult onset is associated with reduced insulin sensitivity, which is, at least in part, related to increased central adiposity . The latter improves within the first 3 months of GH replacement but this does not result in an immediate improvement in insulin sensitivity . In fact, because of the antagonistic effects of GH on the actions of insulin mediated by hepatic effects, and the increase in circulating free fatty acids, there is on average a further decline in insulin sensitivity, which subsequently returns to baseline over the first year of GH replacement therapy . The decline in insulin sensitivity during GH therapy is associated with a slight elevation of fasting plasma glucose and a parallel increase in glycated hemoglobin, both within the normal reference range. Importantly, the increment in glycated hemoglobin is not evident in patients with prior abnormalities of glucose tolerance but is significantly correlated with baseline body mass index, the latter emphasizing the importance of additional dietary and lifestyle advice in these patients.
How The Test Is Performed
Blood is drawn several times. Blood samples are taken through an intravenous line instead of reinserting the needle each time. The test takes between 2 and 5 hours.
The procedure is done the following way:
- An IV is usually placed in a vein, most often the inside of the elbow or the back of the hand. The site is first cleaned with germ-killing medicine .
- The first sample is drawn early in the morning.
- Medicine is given through the vein. This medicine stimulates the pituitary gland to release GH. Several medicines are available. The health care provider will decide which medicine is best.
- Additional blood samples are drawn over the next few hours.
- After the last sample is taken, the IV line is removed. Pressure is applied to stop any bleeding.
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How Long Does My Child Have To Take The Growth Hormone
You will give your child the growth hormone until he or she has stopped growing. While your child is taking the growth hormone, he or she will need lab tests and doctor visits every 3-6 months. This is to make sure your child is taking the right dose and to make sure there are no side effects. Many children who have growth hormone deficiency do not have it once they are teenagers. When your child has stopped growing, he or she will most likely go off growth hormone for at least one month. Then, we will retest him or her for growth hormone deficiency. If tests show that he or she still has growth hormone deficiency, your child might start taking a lower dose again once he or she is a teenager.