Growth Hormone Stimulation Tests

A growth hormone stimulation test measures how well the pituitary gland makes growth hormone. The pituitary gland is part of the body’s endocrine system. Your child needs growth hormone to grow normally.

At St. Jude, this testing may be ordered either by the Endocrine Clinic or the Radiation Oncology Clinic. There are 2 types of growth hormone stimulation tests:

• The arginine glucagon test, which is ordered by the Endocrine Clinic
• The arginine carbidopa-levodopa test, which is ordered by the Radiation Oncology Clinic

The care team will collect blood samples during the test to measure the amount of growth hormone released in the blood samples.

How to prepare for growth hormone stimulation testing

Your child will need to follow fasting guidelines or NPO (nothing by mouth) guidelines for when to stop eating and drinking. Eight hours before the time of your child's test, stop giving them solid food, enteral (tube) feeds, and all liquids except for water.

On the morning of the test, give your child their usual medicines, unless your child’s care team tells you not to do so.

Testing will take place at either the Endocrine Clinic or Radiation Oncology Clinic, depending on who ordered the test.

Have your child wear comfortable clothes. Bring activities such as books, games, or tablets that they can do during the test.

What to expect during growth hormone stimulation testing

You can stay with your child during the growth hormone stimulation test. Before the test, the care team will place an IV in your child’s arm.

The care team will give 1 of these medicine combinations during the test, depending on what your care provider ordered:

During the test, the care team will draw small blood samples through the IV for testing in the lab. The nurse will also check your child’s vital signs and blood sugar levels.

At the end of the test, your child will have a snack and the nurse will remove the IV.

Possible risks or side effects of growth hormone stimulation testing

The side effects depend on the type of stimulation used.

• For the arginine glucagon stimulation test at the Endocrine Clinic, the medicines can cause low blood sugar. Your child may feel tired or weak. Rarely, children may have nausea and vomiting during the test.
• For the carbidopa-levodopa at the Radiation Oncology Clinic, your child may experience nausea and vomiting.

After growth hormone stimulation testing

Your child may be hungry. They can eat and drink normally after the test. For the rest of the day, your child should take it easy and avoid too much activity.

Your child will be able to return to normal activities the next day.

Your health care provider will discuss your child’s test results with you.