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Several variants of growth hormone testing are now available. They are GH serum test, Insulin-like growth factor-1 test, GH suppression test, and GH stimulation test.

Human growth hormone (HGH) is produced by the pituitary gland and secreted into the bloodstream in pulses at various points throughout the day.

These pulses range from between 10 and 30 per day and can be strengthened by exercise. As the name suggests, growth hormone is essential for normal growth and development in children. Although not as active in adults, GH helps regulate bone density, muscle mass, and lipid metabolism, and is important for tissue repair, muscle growth, bone strength, brain function, physical and mental health, energy, and metabolism.

There are a few variants of human growth hormone testing:

  1. GH serum test
  2. Insulin-like growth factor-1 test
  3. GH suppression test
  4. GH stimulation test

1. An HGH Serum Test is ordered to assess pituitary function and help diagnose conditions resulting from the deficiency or overproduction of the human growth hormone (HGH) such as hypothalamic disorder, hypopituitarism, acromegaly, and ectopic growth hormone production by neoplasm. The test measures the amount of growth hormone in the blood.

The HGH Serum Test is also commonly referred to as simply GH, HGH, or Human Growth Hormone, as well as Somatotropic Hormone, Somatropin, or STH. To prepare for this blood test, patients are asked to fast for 10-12 hours and rest for at least 30 minutes prior to collection. Test results will be available within 2-3 days. Insurance is not required to order this test. Patients also do not need a doctor’s order.

The HGH Serum Test is often ordered along with an IGF-1 Blood Test. Since HGH is secreted in pulses throughout the day, a single test may not accurately show a deficiency or excess. Insulin-like growth factor (IGF) mirrors GH, but IGF is stable throughout the day, and as a result, maybe a more accurate indicator of average GH levels.

2. Insulin-like growth factor-1 (IGF-1) is a hormone that, along with growth hormone (GH), helps promote normal bone and tissue growth and development. The test measures the amount of IGF-1 in the blood.

IGF-1 is primarily produced in the liver, skeletal muscles, and many other tissues in response to GH stimulation. IGF-1 mediates many of the actions of GH, stimulates the growth of bones and other tissues, and promotes the production of lean muscle mass. IGF-1 also plays a role in non-growth activities, such as glucose and lipid metabolism, and has been implicated in metabolic syndrome.

Since GH is released into the blood in pulses throughout the day, it is difficult to interpret the results from a single GH test. IGF-1 mirrors GH excesses and deficiencies, but unlike GH, its level is stable throughout the day. This makes IGF-1 a useful indicator of average GH levels. The IGF-1 test is therefore often used to help evaluate for GH deficiency or GH excess.

3. The growth hormone suppression test determines whether growth hormone (GH) production is being suppressed by high blood sugar.

At least three blood samples are taken.

The test is done in the following way:

  • The first blood sample is collected between 6 a.m. and 8 a.m. before you eat or drink anything.
  • You then drink a solution containing glucose (sugar). You may be told to drink slowly to avoid becoming nauseated. But you must drink the solution within 5 minutes to ensure the test result is accurate.
  • The next blood samples are usually collected for 1 to 2 hours after you finish drinking the glucose solution. Sometimes they are taken every 30 or 60 minutes.
  • Each sample is sent to the laboratory right away. The lab measures the glucose and GH levels in each sample.

4. Depending on the clinic or facility where you undergo a GH stimulation test, the specific procedure may vary slightly. In general, here’s what you can expect if a doctor orders a GH stimulation test for you or a family member:

A healthcare provider will place an IV (intravenous line) in a vein in your arm or hand. The procedure is similar to a blood test. The major difference is that a small needle connected to a tube that is part of the IV stays in your vein.

You may experience some discomfort when the needle pierces your skin, and some bruising afterward, but the risks and side effects are minimal.

A healthcare provider will take an initial blood sample through the IV. This and all later samples will most likely be collected using the same IV line.

Then you will receive a GH stimulant through the IV. This is a substance that typically encourages an increase in GH production. Some commonly used stimulants are insulin and arginine.

Next, a healthcare provider will take several more blood samples at regular intervals. The entire procedure usually takes about three hours.

After the test, laboratory professionals will analyze your blood samples to see whether your pituitary gland has produced the expected amount of GH in response to the stimulant.

Growth Hormone Test Preparation

The growth hormone test requires fasting after midnight that means no breakfast or fluids except for normal water. This Human growth hormone test should not be carried out if the person is sick. Inform a doctor about any allergies as well as any medications being used as certain kinds of medication can lead to false test results.

Growth Hormone Test Procedure

The Growth hormone stimulating test or growth hormone test is a long procedure and can take up to 6 hours to complete. In the test, an IV line will be started and blood samples will be drawn out from the IV itself and L – Arginine and Cortrosyn. The blood samples can be drawn every 30 minutes for up to 4 hours.

When to get tested for growth hormone?

The growth hormone test is advised if the following factors are noticed;

  • slow growth;
  • short stature;
  • delayed development;
  • decreased bone density;
  • elevated blood lipid levels;
  • symptoms of excessive GH;
  • symptoms of HGH deficiency;

Growth Hormone Normal Range

  • The growth hormone normal range in a healthy Men < 5 ng/mL or < 226 pmol/L
  • For women the growth hormone normal range is < 10 ng/mL or < 452 pmol/L
  • For children, the growth hormone normal range is 0-20 ng/mL or 0-904 pmol/L

High Levels of Growth Hormone

The main cause of elevated growth hormone is a pituitary tumor composed of somatotropic cells. These tumors are benign and grow slowly and overtime keep producing excess human growth hormone. Excess human growth hormone (HGH) can result in gigantism, acromegaly, headaches, impaired vision, and can result in deficiency of the pituitary hormone.

Growth Hormone Deficiency

Growth hormone deficiency is mainly caused by alterations in the somatomedin. It can result in growth failure, short stature, and delayed sexual maturity. Although this deficiency is a rarity it can result in weaker bones and osteoporosis.

Growth Hormone Deficiency Symptoms

The common growth hormone deficiency symptoms are as follows;

  • shorter stature and chubbier appearance;
  • delayed puberty;
  • reduced bone strength;
  • some of the psychological symptoms of HGH deficiency are;
  • depression
  • lack of concentration
  • low memory
  • anxiety
  • emotional distress

If you’ve go any suspicious symptoms or you observe some of them in your kid don’t hesitate to undergo HGH testing as soon as possible. If you’ve got any additional questions or suggestions, please be sure to contact our team of qualified experts and we’ll get back to you very soon.