The Arginine test determines whether the pituitary gland is producing normal levels of human growth hormone. The arginine test will determine the levels of human growth hormone present in your blood, and the pituitary glands ability to release HGH.
This test determines whether the pituitary gland produces normal amounts of growth hormone.
- A baseline of growth hormone and somatomedin –C levels is established.
- The area is cleaned using an antiseptic wipe in preparation of the IV. The IV is usually placed in a vein either on the back of the hand or the inside of the elbow. The health care provider will wrap an elastic band around the patient’s upper arm to make the vein swell with blood. The needle is then inserted into the vein, and the band is removed.
- Your blood will be drawn 5 times over the course of 60 minutes. The first draw is taken between 6 am and 8 am.
- The patient is injected intravenously with Arginine over a 30 minute interval. The amount of Arginine is determined by body weight.
- After the 30 minutes, it is followed by an intravenous injection of GHRH.
- The growth hormone levels are then checked at 15 minute intervals until 60 minutes. If the growth hormone level does not increase after the stimulation test then it is possible that a person might be HGH deficient. Usually other tests are done to rule out other causes.
Preparing for the Test
- Do no eat for 10-12 hours prior to the test to ensure you do not affect the results.
- Limit your physical activity for 10 to 12 hours before the test.
- Your doctor might tell you to stop taking certain medications prior to the test. You should not do this without talking to your doctor.
- You will be told to relax for at least 90 minutes prior to your arginine test. That’s because exercise or any increase activity can affect the HGH levels in the body.
- If it is a child that is receiving the test you should talk to them about the IV so that they are not scared.
How the Test Feels
There may be moderate pain when the needle is inserted, or you may just feel a stinging sensation, or a slight prick. This depends on the patient and the nurse. There could be some bruising and throbbing at the site where the needle was inserted. These are temporary symptoms and will disappear quickly.
Why the Test is Performed
This test is typically generally performed when your doctor suspects a human growth hormone deficiency.
- Normal peak value — at least 10 ng/mL
- Indeterminate — 5 – 10 ng/mL
- Subnormal — 5 ng/mL
Normal value ranges can vary slightly from one laboratory to the next. This information is provided only as a general guide. You should always discuss your results with your doctor.
What Does it Mean if You Have Abnormal Results
If the arginine stimulation test does increase your GH levels, it means that your pituitary gland is capable of producing HGH.
In the case a person is HGH deficient the treatment generally involve HGH injections, although only your doctor should determine the right course of action for you.
Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevie
Parks JS, Felner EI. Hypopituitarism. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier