The Stimulation Test Date Time Place Dr./Nurse Phone 45364_elhmtp_HG64712_stim_br_fa3.indd 3 7/28/10 1:46:55 PM
What You Should Know About Your Child s Stimulation Test 2 Key Terms 3 Normal Growth 4 Evaluation by a Growth Specialist 5 Growth Hormone Deficiency 6 Stimulation Test 7 What to Expect 9 Checklist 10 Questions & Answers Your child s doctor has ordered a Growth Hormone Stimulation Test to gain more information about hormones affecting your child s growth. This booklet will help you understand the purpose of the stimulation test and what to expect before, during, and after the test. You will learn about normal growth, how growth hormone deficiency can affect growth, and how growth hormone deficiency is diagnosed. A list of key terms, a checklist, a question-and-answer section, and a list of additional resources are included. 11 Questions to Ask the Doctor 45364_elhmtp_HG64712_stim_br_fa3.indd 3-1 7/28/10 1:46:57 PM
2 Key Terms Normal Growth 3 These are just a few of the terms you may read or hear in relation to your child s stimulation test. There is additional space on page 11 to list other words or terms that you may want to ask your child s doctor or nurse. Endocrine Glands: Glands that produce hormones that are carried by the bloodstream to stimulate other parts of the body to perform certain functions. Endocrinologist: A doctor who specializes in conditions of the endocrine glands and their functions. Growth: Change in size of cells, tissues, organs, or whole organisms. Growth Hormone: One of the key hormones responsible for growth in childhood. It is produced by the pituitary gland. Figure 1 shows where the pituitary gland is located. Hormones: Chemical messengers produced by cells in the endocrine glands. Hypothalamus: An important part of the brain that links the nervous system with the endocrine system. The hypothalamus sends messages to the pituitary gland, which is connected to it by a fine stalk. These messages control how the pituitary gland works (see Figure 1). Insulin-like Growth Factor I (IGF-I): An intermediate hormone in growth. IGF-I transmits messages from the sender (growth hormone) to the receiver (the tissues). When the body s tissues receive the IGF-I message, the cells grow. Because IGF-I is produced by the tissues only when instructed by growth hormone, the amount of IGF-I in the blood can act as a clue to the amount of GH the body is making. Pediatric Endocrinologist: A doctor who specializes in the development, care, and treatment of children with endocrine disorders. Many pediatric endocrinologists are growth specialists. Pituitary Gland: A pea-sized gland at the base of the brain, often called the master gland. Figure 1 Section through the brain showing: Hypothalamus Pituitary Gland We all start out about the same size at birth, but a person s adult height is determined by many factors, including the height of each parent. Table 1 provides the normal ranges for how fast children grow at different ages. Values are rounded and are approximate. Normal children may grow faster or slower than these rates at certain times. Growth rates are particularly variable in the first 2 years of life. Therefore, these values (*) allow for some catch-up or catch-down. As you ll see from this table, most children will grow at a rate of at least 2 inches each year in the period before puberty. A child who grows less than 2 inches in a given year should be evaluated for a growth problem. 1 Reference 1. Rieser PA. Patterns of growth. The Human Growth Foundation. www.hgfound.org/pub_patterns.html. Accessed July 2, 2010. Table 1 Growth Rates (Velocities) During Childhood Age Average Growth Per Year Inches Centimeters Birth to 1 year 6.7 13.8 17.0 35.0* 1 2 years 3.2 6.3 8.0 16.0* 2 3 years 3.0 3.9 7.5 10.0** 3 5 years 2.2 3.3 5.5 8.5** 5 years to puberty 2.0 3.0 5.0 7.5** During puberty 3.0 4.1 7.5 10.5** After puberty 0.4 1.2 1.0 3.0** * Calculated on the basis of cross-sectional data obtained from Vital and Health Statistics Data from the National Health Survey Series II, Number 165, Publication No. 781650, U.S. Department of Health, Education and Welfare. ** From longitudinal data reported by Tanner JM, Davies PS. Clinical longitudinal standards for height and height velocity for North American children. J Pediatr. 1985;107(3):317-329. 45364_elhmtp_HG64712_stim_br_fa3.indd 2-3 7/28/10 1:46:58 PM
4 Evaluation by a Growth Specialist Growth Hormone Deficiency 5 Some information and tests your child s doctor may need in order to determine whether your child has a growth problem are outlined below. 1 The height of family members and any health problems present in the family. 2 Details of the mother s pregnancy, labor, and delivery. 3 All measurements of the child s height and weight since birth (if records are not available from your family doctor, then school records may be a good source of information). 4 Information about the child s general health, eating habits, past illnesses, injuries, and any emotional or physical stresses. 5 A detailed physical examination to look for any physical clues to the cause of poor growth. 6 An x-ray of the hand and wrist to see how bone development compares to the child s age. 7 Blood tests to look for evidence of diseases, such as kidney, stomach or bowel disorders, or hormone imbalances, including deficiencies of thyroid hormone or growth hormone. Growth Charts A growth chart is an important tool used to determine whether a child has a growth problem. By plotting a child s measurements on a growth chart over time, a doctor can determine whether a child is growing normally. If a child fails to grow over a period of time or is much shorter than other children of the same age, tests may be required to determine the cause. The growth specialist may wish to observe the child s growth over a 6- to 12-month period and may perform a series of blood tests to measure levels of a number of important chemicals and hormones. What is Growth Hormone Deficiency? This occurs when the pituitary gland does not make enough growth hormone. This deficiency in growth hormone results in a slower rate of growth for a child. What Causes Growth Hormone Deficiency? There are a number of possible reasons for low growth hormone production in childhood. In some cases, there may have been improper formation of the hypothalamus (the region of the brain that controls the pituitary gland) or pituitary gland before birth. Head injuries, brain tumors, and brain damage due to disease or radiation can also affect the functioning of the pituitary gland. Various tests may help to identify the cause of deficiencies in pituitary function. To help determine whether the pituitary gland is able to make enough growth hormone, a stimulation test may be needed. The following section of this booklet describes this procedure in detail. About 1 in 3500 children in the United States are diagnosed with growth hormone deficiency. 2 Reference 2. Lindsay R, Feldkamp M, Harris D, et al. Utah Growth Study: growth standards and the prevalence of growth hormone deficiency. J Pediatr. 1994;125(1):29-35. 45364_elhmtp_HG64712_stim_br_fa3.indd 4-5 7/28/10 1:47:00 PM
6 Stimulation Test What to Expect 7 The growth specialist will try to determine whether your child s pituitary gland is making enough growth hormone. To help evaluate this, your child s growth specialist has scheduled a stimulation test. Various stimulating agents, or stimuli, will be used to trigger the release of growth hormone by the pituitary gland. These stimuli include a number of medications and other substances that cause the pituitary gland to release a short burst of growth hormone. One or two stimulating agents are given, and then blood samples are collected over a period of time. The samples are sent to a laboratory, where the level of growth hormone in the blood is measured. The response to these stimuli will help determine whether sufficient growth hormone is being produced. This test is sometimes called a provocative test because it is designed to provoke a response in the pituitary gland s release of growth hormone. Medicine(s) to Be Obtained Before the Appointment Before the test, your child s doctor may give you a prescription for certain medicine(s) that will be needed for the test. If so, get the prescription filled and bring the medicine(s) with you to the appointment. Check with your pharmacist at least a week before your appointment to be sure the medicine(s) will be available when needed. Preparing for the Test Normally your child should not have food or liquid the night before such a procedure. Make sure to check with your child s doctor. If your child is receiving any medication, ask your child s doctor or nurse what to do about any doses that may be required between midnight and the test appointment time. In particular, if your child has diabetes or low blood sugar, ask your child s doctor or nurse for special instructions several days before the test is scheduled. Your child may want a snack after the testing is done, so you may wish to bring some food or drink with you. Your Child You may want to bring your child s favorite blanket, pillow, or toy. Because it is important to keep your child as quiet as possible with minimal activity during the testing, you may wish to bring books or some other quiet activities (music, games). It s a good idea to dress your child in loose-fitting clothing and a short-sleeved shirt with buttons down the front (for easier insertion of the intravenous [IV] needle). Your child will be kept comfortable. Sometimes a recliner, a hospital bed, or an exam table is used. What Happens During the Test The following procedure is provided as an example this may vary somewhat at different facilities. First, your child will be made comfortable in a recliner or bed. Then the skin on your child s hand or arm where the needle is to be placed will be cleaned. 45364_elhmtp_HG64712_stim_br_fa3.indd 6-7 7/28/10 1:47:06 PM
8 Checklist 9 Your child may be given something to numb the skin where the IV needle will be inserted. Then the IV needle will be inserted. The first blood sample will probably be taken at this time. After the needle is in place, a medicine or stimulating agent will be given either by mouth or via the IV line. Following this, your child will need to remain fairly inactive. Additional blood samples will be collected over the next few hours. A second medicine may be given at the same time as the first, or about halfway through the test. After all of the samples have been collected, the IV needle will be removed and a bandage or gauze applied. The blood samples collected during the test will be sent to a laboratory for measurement of the growth hormone levels. From these measurements, your child s doctor will be able to tell how the pituitary gland responded to the stimuli. After the Test When the testing is done, your child may want to eat a snack. Suggestions include something with quick energy or simple sugar (for example, fruit juice) and something with protein (peanut butter on crackers is a good source). Your child may feel tired or weak and may want to rest after the test is done. Stay with your child, if possible, or have someone available to supervise him or her for the rest of the day. Ask your child s doctor when to expect the results of the test. Please use the checklist only as a guide, because the list is not comprehensive. 1 Week Before the Test Talk with your child about the appointment, when you will be going, and why the test is important. If you have been instructed to get certain medicine(s), have prescription(s) filled at the pharmacy. You may need to check with your insurance provider for pre-authorization to cover costs. Check with your child s doctor or nurse regarding what to do about medications your child is scheduled to take on the night before or the day of the test. 1 Day Before the Test Remind your child about the test and where you will be going tomorrow. If you had to get any prescription medicine(s), have these ready. Choose a favorite toy, blanket, or books for your child to have during the test. Choose loose-fitting clothes for your child to wear to the appointment. And remember, normally your child should not have food or liquid the night before such a procedure. Make sure to check with your child s doctor. Day of the Test Prepare snack foods for your child to have after the test. Plan to arrive for the appointment about 30 minutes ahead of schedule to avoid last-minute stress. Keep your child calm with minimal activity. After the Test If your child is feeling OK, check with the doctor or nurse as to whether your child can be given a snack. Discuss any special care for your child or the need for additional appointments or instructions. 45364_elhmtp_HG64712_stim_br_fa3.indd 8-9 7/28/10 1:47:07 PM
10 Questions & Answers Questions to Ask the Doctor 11 What should I do if my child is sick? If your child becomes sick, doesn t feel well, or has been exposed to any contagious disease, call your child s doctor or nurse for further information. How long does the test take? The test may take several hours on one day or it may occur over a 2-day period. The total time may vary depending on which medicines are used and how many blood samples are taken. Who will perform the test? A nurse usually performs the test; check with your child s doctor for more details. Can I stay with my child during the procedure? Depending on the facilities where the testing takes place, you may be able to stay with your child. Do the testing procedures hurt? Your child may feel a pinching, pricking, or burning sensation when the needle is put into the vein in his or her arm or hand. If an intravenous medicine is used, this may cause stinging, a hot or cold feeling in the vein, or a funny sensation. Are there any risks or side effects to the test? Your child may feel tired and weak depending on the medicines used in the test, the duration of the test, and other factors. In addition, some children may become nauseated or feel warm during or after the test. Be sure to discuss potential side effects with your child s doctor or nurse. Ask your child s doctor or nurse for suggestions that might reduce the discomfort. How long will it take to get the results? The time will vary from one facility to another, but results could take up to 2 weeks. Ask your child s doctor whether you should call to get the results or if someone will contact you. 45364_elhmtp_HG64712_stim_br_fa3.indd 10-11 7/28/10 1:47:08 PM
There are several tests a doctor can perform to help determine the cause of a growth problem. The stimulation test is one way to determine how much growth hormone your child s pituitary gland makes. The results from this test may help determine whether your child has growth hormone deficiency. The information in this booklet will help you and your child prepare for the stimulation test. Remember, it is very important to always follow your child s doctor s instructions. If you have any questions, ask your child s doctor or nurse for more information. Support Groups Several organizations provide support and educational programs for families of children with growth disorders. Contact these organizations for information on services and local chapters. Human Growth Foundation 997 Glen Cove Avenue, Suite 5 Glen Head, NY 11545 1.800.451.6434 www.hgfound.org The MAGIC Foundation 6645 W. North Avenue Oak Park, IL 60302 1.800.3 MAGIC 3 (1.800.362.4423) www.magicfoundation.org Turner Syndrome Society of the United States 11250 West Road, Suite G Houston, TX 77065 1.800.365.9944 www.turnersyndrome.org 45364_elhmtp_HG64712_stim_br_fa3.indd 12-3 7/28/10 1:47:16 PM
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