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The causes of increase and decrease in growth hormone
Last reviewed: 19.10.2021
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Increase in the concentration of growth hormone in the blood serum is observed with acromegaly (in 80% of patients - more than 10 ng / ml) and gigantism, which are more often associated with growth hormone - the production pituitary adenoma. The main method of laboratory diagnosis of gigantism and acromegaly is the determination of the concentration of growth hormone in the blood serum on an empty stomach (the mean value of the 3-fold determination is calculated over 2-3 days with 1-2-day intervals). Usually the concentration of growth hormone in the blood in patients is 2-100 times higher than normal (sometimes reaches 400 ng / ml). At close to normal levels of fasting hormone in the blood, fasting (in 30-53% of patients) to confirm the diagnosis and establish the phase of the disease (active or inactive), it is necessary to investigate the daily rhythm of growth hormone secretion (in the active phase exceeds normal values 2-100 times and more), as well as carry out a series of physiological and pharmacological tests. To clarify the diagnosis, the content of somatotropic hormone in the serum is examined at intervals of 1-2 months. In acromegaly, determination of somatotropic hormone in the blood serum in the dynamics of the disease is necessary to assess the effectiveness of conservative therapy and the radical nature of surgical treatment. Medication for acromegaly is considered adequate if the concentration of growth hormone does not exceed 10 ng / ml. Effective gamma or proton therapy leads to a normalization of the concentration of somatotropic hormone in the blood. The result of gamma-therapy is estimated not earlier than 2 months, and proton therapy - after 4 months after the end of treatment. Radically performed surgery also helps normalize the content of growth hormone for several days. Completeness of removal of somatotropinoma is assessed using a glucose-tolerance test with the study of the content of growth hormone in the blood serum on an empty stomach, and also at 1 and 2 hours after the intake of glucose. A decrease in the concentration of growth hormone during the test to 2.5 ng / ml and below indicates a radical adenomectomy.
The lowered secretion of growth hormone during the growth period leads to dwarfism. In pituitary tuberculosis, the secretion of growth hormone is reduced, the daily rhythm of secretion is not traced. If the content of the growth hormone exceeds 10 ng / ml in a sample taken on an empty stomach, its insufficiency can be ruled out. At lower values, more research is needed. Various diagnostic tests are performed, since the lower limit of the normal concentration of growth hormone in the blood is close to the sensitivity limit of existing laboratory methods for determining it.
More recently, the insufficiency of the growth hormone in adults has been isolated into an independent nosological form. Clinically, the inadequacy of growth hormone in adults is manifested by an increase in body weight due to the growth of adipose tissue, a decrease in the amount of fluid in the body (mainly due to extracellular) and bone mineral density. In the blood, an increase in the concentration of VLDLP, LDL, TG and a decrease in HDL is revealed (normalization of their level is an important criterion for evaluating the effectiveness of substitution treatment in such patients). The concentration of IAPF I in serum as a criterion of growth hormone insufficiency in adults is not used because of the considerable variability in the reference values.
The concentration of growth hormone in the blood can decrease in children with primary hypothyroidism. Successful treatment of hypothyroidism leads to its normalization.