I. Secretion and regulation of growth hormone Characteristics: Pulsatile secretion Frequency: about 3-5 hours apart, about 8 pulses/day Ina Shen, Department of Pediatrics, Yiji Mountain Hospital, Wanan Medical College Peak: secretion reaches its peak one hour after sleep, and the secretion is more than half of the total amount of the day, so sufficient sleep is important Secretion site: Secretion from the anterior pituitary gland Regulation mechanism: regulated by two neurohormones secreted by the hypothalamus – growth hormone releasing hormone (GHRH) Growth hormone releasing inhibitory hormone (SRIH) 2. Reasons for the excitation test 1. The peak level cannot be detected by random blood collection, unlike thyroid hormone and other hormones whose concentration is usually constant in the blood, which can be examined by blood collection at any time; 2. It cannot be used as a basis for diagnosis. It only appears 3 to 5 peaks during deep sleep at night, but the child may wake up during night blood collection, and the number of blood collection needs to be more for a long time, so it cannot be used.
3. Growth hormone stimulation test method: 1. Fasting from 21:00 the night before the stimulation test, you can drink less water and perform the test in the early morning of the next day on an empty stomach, without eating during the whole process, drinking less water, and it is better for the child to enter the sleep state; 2. Do the growth hormone stimulation test of two drugs separately to avoid a false positive of 15% for one drug; 3. The drugs used in the stimulation test done by our hospital are colistin and arginine. Colistin has a certain hypotensive effect, and arginine is an essential amino acid that can be produced naturally in the body; 4, the route of administration of the stimulation test: oral and intravenous, respectively, using two types of oral and intravenous medication, which can reduce the possibility of rapid effect of oral drugs due to digestion and absorption.
5.The time and number of blood collection for the stimulation test: ①Blood collection of 1.5ml once before drug administration to determine the basic growth hormone value, marked as colistin 0 minutes ②Blood collection of 1.5ml once half an hour after oral colistin, marked as colistin 30, 60 and 90 minutes respectively; ③After colistin 90 minutes blood collection, flush the tube and directly infuse arginine solution intravenously to ensure the end of infusion within half an hour. The first drop of arginine drop into the body to record the time, half an hour after the blood collection 1.5ml marked as arginine 30 minutes, and every half an hour thereafter 1.5ml of blood collection, marked as arginine 60, 90, 120 minutes, respectively.
6. Judgment of growth hormone stimulation test results: Any GH peak ≥ 10ng/ml is normal; GH peak < 5ng/ml is complete lack; 5ng/ml < GH peak < 10ng/ml is partial lack; IV. Possible problems during the stimulation test: 1. Why does the child appear dizzy during the stimulation test? A: Because colistin has a partial hypotensive effect, many children feel dizzy, which is a normal phenomenon, rest and lie down can be relieved. Our hospital closely monitors the changes in the blood pressure of the child during the whole test, and measures the blood pressure of the child every half hour and records it. 2.Will too much blood be taken to harm the child’s body? The human spleen is used to destroy mature red blood cells, and it destroys about 30ml per day. After we draw blood, the spleen will compensate for less destruction, which will not cause any damage to the child. V. Need for growth hormone stimulation test The growth hormone stimulation test uses two different drugs to stimulate the maximum amount of growth hormone secretion in the body from two different ways, and the peak growth hormone is taken from the laboratory results for diagnosis, which is a confirmatory test to determine whether the child is growth hormone deficient.