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Growth hormone, usually secreted in episodic bursts during early sleep, promotes skeletal growth by stimulating liver production of proteins, and affects lipid as well as glucose metabolism. Growth hormone also increases blood flow to the kidneys. It is believed to antagonize Insulin. There are several test methods to detect human growth hormone levels, namely, Somatotropin hormone test, Somatomedin C, Growth hormone stimulation test and Growth hormone suppression test.
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Somatotropin Hormone Test
Somatotropin test is one of the test method to detect human growth hormone levels in the blood. Excess levels may occur in both children and adults. In adults it causes the bones of the skull, hands, and feet to thicken resulting in acromegaly. In children, it causes the long bones of the body to increase in size often resulting in gigantism.
Decreased levels of growth hormone happens mostly in children, which results in very small statures but with normal body proportions, and is known as pituitary dwarfism.
This test is done through blood collection which is performed for two consecutive days anytime between six to eight in the morning. The patient is advised to fast from food and should avoid strenuous exercise for 12 hours before each sample is taken. Before the sample is drawn, the patient is recommended to have bed rest for at least an hour.
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Growth Hormone Suppression Test
Another name for the growth hormone suppression test is glucose loading test. This test is frequently used to confirm cases of acromegaly in adults and gigantism in children. Two blood samples are usually taken, one before ingestion of one hundred grams of glucose. The next one is taken after two hours of taking the glucose load. Persistently high results often indicate dysfunction in the anterior pituitary.
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Somatomedin C Test
Sometomedin C test is also known as Insulin-like Growth Factor or IGF-1. It is used to assess pituitary function, and to observe the effectiveness of treatment for growth hormone replacement. It is said to be more reliable and stable than the growth hormone test. It is also done through a blood test. Decreased levels may mean deficiency in growth hormone level, hypothyroidism, nutritional deficiencies, or severe liver disease. Increased levels may indicate increased growth hormone level, pituitary tumor, or hyperpituitarism.
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Growth Hormone Stimulation Test
Growth hormone stimulation test is also known as insulin tolerance test, human growth hormone provocation test, and arginine test. It is usually done to evaluate the capacity of the body to create human growth hormone, to determine a possible decreased human growth hormone production, and to confirm diagnosis of acromegaly. The procedure consist of taking a venous sample through a venous access at eight in the morning, then 3 stimulants are administered. The first one, levodopa, is taken orally. Insulin and arginine are then administered intravenously, after which three blood samples are taken through the venous access at thirty minute intervals each.