The diagnosis of short stature in children is based on the test results.
I. Growth hormone secretion and regulation Secretion and regulation of growth hormone
Characteristics: Pulsatile secretion, age-related, with the largest pulse amplitude and the largest amount of secretion in the middle of puberty.
Frequency: about 3-5 hours apart, about 8 pulses/day. Zhang Jing, Department of Pediatric Internal Medicine, First Affiliated Hospital of Zhengzhou University
Peak: secretion peaks one hour after sleep, and the secretion is more than half of the total amount of the day.
Regulation: The hypothalamus secretes two neurohormones
Growth hormone-releasing hormone (GHRH)
Growth hormone-releasing inhibitory hormone (SRIH)
The central nervous system regulates the secretion of GHRH and SRIH through neurotransmitters such as dopamine, 5-hydroxytryptamine and norepinephrine.
II. Reasons for the stimulation test.
1. growth hormone is secreted in the body in peaks, which are usually very low (0-5ng/ml is normal) and only appear in 3-5 peaks at night during deep sleep (the child may wake up during nighttime blood collection, and more blood collection is needed for a longer period of time, so it is not used).
2. The peak level cannot be detected by random blood collection, unlike thyroid hormone and other hormones whose concentration is usually constant in the blood and can be checked at any time by blood collection.
3. Only the usual value cannot reflect whether the growth hormone is normal or not.
III. Method of growth hormone stimulation test.
1. The test is performed in the early morning without exercise and on an empty stomach. Fasting from the night before the test should be at least 8 hours for children >2 years old and 6 hours for infants <2 years old. Fasting during the whole test. 2.
2. In accordance with the treatment protocol for growth hormone deficiency, the growth hormone stimulation test must be done separately for both drugs (to avoid a 15% false positive rate for one drug).
3. stimulation test drugs: combined drugs (two of insulin, colistin, arginine, levodopa, etc.)
4. the route of administration of the stimulated test: oral and intravenous; two types of oral and intravenous drug administration, respectively, can reduce the possibility of rapid effect of oral drugs due to digestion and absorption.
5. Time and frequency of blood collection for the stimulation test: Blood is collected once before the administration of the drug to determine the basal growth hormone value; blood is collected 30, 60, 90 and 120 minutes after the administration of the drug to measure the growth hormone level;
6. Growth hormone stimulation test results judgment: GH peak value ≥ 10ng/g
GH peak value ≥ 10ng/ml at any one time is considered normal;
GH peak < 5ng/ml is considered as complete deficiency;
5ng/ml < GH peak < 10ng/ml is partial deficiency;
(Complete deficiency is distinguished from partial deficiency, not the complete absence of growth hormone in the body)
GH stimulation test is currently the main tool for the diagnosis of growth hormone deficiency dwarfism (GHD).
IV. Explanation of the problems with the stimulation test.
1. Why did the child become dizzy during the stimulation test?
A: Because colistin has a hypotensive effect, many children feel dizzy, which is a normal phenomenon.
2. Will too much blood collection harm the child’s body?
A: In fact, there is no need to worry, the total amount of blood collected does not exceed 15ml, the human spleen is used to destroy mature red blood cells, about 30ml per day, after we draw blood, the spleen will compensate for the destruction of some.