Endocrinology Testing in Day Medicine: Growth Hormone Stimulation Test

These instructions are for Children's Hospital of Philadelphia patients who are scheduled for growth hormone stimulation testing to determine if their bodies make enough growth hormone.

Important information about growth hormone stimulation testing:

Your child is scheduled to have growth hormone testing to determine if their body makes and releases the right amount of growth hormone. Learn more about growth hormone deficiency.

During growth hormone stimulation testing, your child will take medicine that causes the pituitary gland to release growth hormone. The amount released will be measured and compared to the normal values for your child's age and gender.

Preparing for the test

Instructions for eating and drinking:

• Children younger than 3 years old: Your child may have plain water (unflavored) before and during the test. They may not have anything else to eat or drink starting 2 hours before the test.

• Children 3 years and older: Your child may have plain water (unflavored) before and during the test. They may not have anything else to eat or drink after midnight. Give a snack just before bedtime to help prevent early morning hunger.

• Encourage extra fluids for two days before the scheduled appointment. This will help your child feel better and may help the team place the IV more quickly.

Instructions for medicine:

• You may give your child their daily medicines the morning of the test, unless your endocrine provider instructs you not to. Contact your provider if your child is taking liquid medicines that may contain sugar.

• Some children are prescribed a medicine called estradiol to take before the test. This pill should be taken at bedtime on the two nights before the test. Be sure to have this prescription filled before your child is scheduled to begin the medicine. If it is not taken as directed, your child's test may need to be rescheduled.

Instructions for the day of testing:

• Growth hormone stimulation tests are performed on the Day Medicine Unit located on the 3rd floor of the Buerger Building. Plan to arrive at your scheduled appointment time. Please allow extra time to park and check in. Your appointment may be rescheduled if you arrive late.

• Plan for childcare for siblings. Due to safety concerns for patients who may have a compromised immune system and limited space on the unit, Day Medicine cannot accommodate siblings.

• If you need to cancel testing, please notify Day Medicine (215-590-1668) ahead of time so the appointment slot can be offered to another patient.

• Please inform Day Medicine if your child has been exposed to chicken pox or another infectious illness the week of their scheduled test.

• Wear short sleeve shirt if possible. If a long sleeve shirt is worn, please be sure it is loose fitting.

• Bring a snack and a drink for your child to enjoy after the test is completed.

What to expect during the test:

• When you arrive, your child will have an IV (intravenous) line placed in the hand or arm. Once this IV is in place, all blood samples needed will be drawn from the IV.

• There is a television in the unit for your child to watch. Bring toys, or books to help keep your child occupied. They will need to remain lying down throughout the study.

There are different growth hormone stimulation tests. Your team will order the test that is right for your child. For each test below, you can expect the following:

Clonidine arginine study

• The test lasts 4 to 5 hours.

• Your child will be given the first medicine, clonidine, as a small pill to take by mouth. If your child has difficulty swallowing pills, it can be crushed and given with a small amount of water.

• Clonidine takes about 60 minutes to reach its peak effect.

  • Clonidine often has side effects that include low blood pressure and drowsiness. To keep your child safe, they will sit or lie down in a reclining chair during the study. We will check their blood pressure often.

  • Sometimes fluids are given through the IV if the blood pressure is lower than expected.

• Blood samples will be drawn from the IV before the medicine, 30, 60, 90, and 120 minutes (about 2 hours) after your child takes the clonidine.

• The second medicine, arginine hydrochloride, will be given through the IV over 30 minutes.

  • There are usually no side effects from arginine. Some children may have nausea.

• Blood samples will be drawn from the IV 15, 30, 45, 60 and 90 minutes after starting the arginine hydrochloride.

• After the last blood draw, your child will need to eat and drink before going home.

Arginine glucagon study

• The test lasts 5-6 hours.

• The first medicine, arginine, will be given through the IV over 30 minutes.

  • There are usually no side effects from arginine. Some children may have nausea.

• Blood samples for growth hormone levels will be drawn from the IV before the medicine and 30, 45, 60 minutes after starting the arginine.

• The second medicine, glucagon, will be given through the IV.

  • Frequent and expected side effects include nausea, vomiting and abdominal cramping.

• Blood samples for cortisol and glucose will be drawn before the glucagon is given. Then blood samples will continue to be drawn for growth hormone, cortisol, and glucose levels at 90, 120, 150, 180 minutes (about 3 hours) after the medicine.

• After the last blood draw, your child will need to eat and drink before going home.

Instructions following the test:

• If your child took clonidine, they may feel sleepy for 4-6 hours after the test. They should take it easy and rest following the test.

• Your child may return to school and their normal activities tomorrow.

• They can eat a regular diet.

• Your child should take any medicines on their regular schedule.

• Your endocrinology team will contact you with the test results as they are interpreted. This can take up to 2-3 weeks.

If you have any questions about the test, call the Day Medicine Unit at (215) 590-1668.

For any other questions or concerns about your child's care, contact the Division of Endocrinology.

Division of Endocrinology and Diabetes

Reviewed on March 1, 2023, by Vaneeta Bamba, MD