Diagnosis and differential diagnosis of nanism is based on data of anamnesis and complex clinical-radiological, laboratory and hormonal examination. In addition to the absolute size of the body, to determine the growth of patients determine a growth deficit - the difference between the growth of the patient and his average rate for the corresponding sex and age; Growth age - conformity of growth of the patient to the certain specifications; standard deviation index
И = М - Мср / δ, where М - patient's growth, Мср - average normal growth for a given sex and age, δ - quadratic deviation from Мср; And less than 3 - is typical of Nanism, And more than 3 - for gigantism. This indicator can be used to assess the dynamics of development.
X-ray study of patients with nazmom allows to identify the presence of signs of intracranial hypertension, residual phenomena of neuroinfection, calcification, craniostenosis. The study of the size, shape and structure of the Turkish saddle is considered as an indirect indicator characterizing the size of the pituitary gland. One of the most important manifestations of pathological growth retardation is the violation of the differentiation of the skeleton. To assess the degree of maturity of the skeleton, the bone (x-ray) age is determined, to which the differentiation of bone tissue corresponds; Deficiency of ossification (ossification) - the degree of ossification of the ossification from the norm (in years), the coefficient of ossification - the quotient from the division of bone age into chronological and other parameters.
Modern diagnostics of nanism is impossible without studying the secretion of somatotropic hormone, its basal level, circadian rhythm, release under stimulation conditions. For most patients with pituitary nazmom characterized by a reduced content of somatotropic hormone in the blood serum. When determined by the radioimmunoassay method, it is (from the data of different authors) from (0.87 ± 0.09) to (1.50 ± 0.64) ng / ml, at an average rate (3.81 ± 0.29) ng / ml. The study of diurnal (circadian) rhythms of secretion of somatotropic hormone showed that its level in healthy people is maximal during the first 2 hours of sleep and at 4-6 hours. During nanism and during these hours, the content of growth hormone is reduced.
To study the reserves of somatotropic function, various stimulants are used, by examining the content of growth hormone before and after their administration. Blood for examination is taken for 2-3 hours every 30 minutes. Normal release of a somatotropic hormone after stimulation is not less than 7-10 ng / ml, sometimes it reaches 20-40 ng / ml. If there is no reaction in one of the samples, repeated tests with other stimulants are carried out. Insufficient growth hormone is considered proven in the absence of a release of growth hormone in 2-3 different samples.
The following stimulating samples are most commonly used: with intravenous injection of 0.1 U (0.75-1.5 U) of insulin per kg of body weight of the patient and achievement of hypoglycemia (decrease of blood glucose level by 50% to the baseline level), serum hormone the above scheme. With the development of severe hypoglycemia, the sample is interrupted, the patient is given intravenous glucose. This is the most common, classical method of diagnosis.
TGH in a dose of 200-500 μg intravenously. Effectively reveals the reserves of the hormone, does not give complications. In combination with the insulin test allows you to judge the level of damage to the hypothalamic-pituitary system. A positive reaction to TRH in its absence on insulin hypoglycemia testifies to the intactness of the pituitary gland and lesion at the hypothalamic level, negative reactions to TRH and hypoglycemia - about the defeat of the pituitary itself.
TGH, LH-RG at a dose of 300 μg is intravenously similar to the previous one.
The human SRH is a synthetic analogue of a biologically active compound isolated from a pancreatic tumor. At present, there are 3 types of synthetic SRH: with 29, 40 and 44 amino acid residues. Applied intravenously in doses from 1 to 3 mcg / kg of body weight of the patient. The release of STH is observed 15-20 min after administration, the test more efficient than others reveals the reserves of endogenous growth hormone. The positive reaction of the STH testifies to the hypothalamic level of the lesion of the somatotropic function and the intactness of the pituitary gland; with amino acids (L-arginine-monochloride, ornithine, tryptophan, glycine, leucine) intravenously at a dose of 0.25-0.5 g per kg of body weight of the patient. Effective for the study of STG reserves. May cause allergic reactions.
L-dopa orally in a dose of 250-500 μg. Effective, well tolerated by patients.
Samples with glucagon, bromergocryptine (parlodel), lysine-vasopressin, clonidine, with a dosed bicycle ergometric load are also used.
The study of the state of somatotropic function is necessary not only for diagnosis of nanism, but also for a reasonable choice of the method of therapy, since treatment with somatotropin is rational only in the case of an inadequate endogenous growth hormone.
For the diagnosis of the form of nanism, it is very important to study the content of insulin-like growth factors, or somatomedins (especially IGF-1, or somatomedin C), the mediators of the action of somatotropic hormone at the tissue level. It is known that the content of somatomedin C in the case of nanism is reduced, and with acromegaly, it is increased in comparison with the norm. The form of nanism described by Laron is a type of disease with normal production of STH, but with a violation of the formation of IRF-1 and IRF-P. Treatment of such patients with somatotropin is futile.
Indirect indicators of somatotropic function of the pituitary gland are the activity of alkaline phosphatase and the content of inorganic phosphorus of serum. With hyposomatotropic conditions, these indicators are reduced. When pangipopituitarnoy form of dwarfism reduced secretion of gonadotropins often TTG, which is accompanied by a corresponding reduction in gonadal function (deficiency of androgens or estrogens), thyroid (falling levels of T 3, T 4, protein-bound iodine - PBI, accumulation of 131 I thyroid gland), adrenal gland ( decrease in the amount of cortisol and 17-ACS in plasma, excretion of 17-KC and 17-ACS in urine, lymphocytosis).
For all types of hypophyseal (hypothalamic-pituitary) genetic nanism, a recurrent disease of children in the family with autosomal recessive (more often) or autosomal dominant type inheritance is characteristic, delay in growth and physical development from 2-4 years with a delay of not less than 2- 3 o from the average growth rates for a given sex, age, population, with a low spontaneous annual growth dynamics, a delay in ossification. At a low level of somatotropic hormone (in 2-3 stimulating tests below 7 ng / ml) therapy with growth hormone is highly effective (gives an increase in growth of at least 7 cm per year). At a normal or high level of growth hormone (with its biological inactivity), the sensitivity to hormone can be maintained. Changes in intelligence are not observed
In genetic nanism with tissue insensitivity to somatotropic hormone, the clinical picture is analogous to isolated growth hormone deficiency, but somatotropin therapy is ineffective. In this group, the following main forms can be distinguished according to the level of IGF: with their normal content (receptor defect in the IGF) and reduced ones - Laron type (IRF-1 and IRP-P deficiency) and type detected in African pygmies (IGF-1 deficiency ).
Cerebral nanism is characterized by single diseases in the family that are associated with intrauterine or postnatal injuries of the central nervous system, with the presence of obvious organic changes in the central nervous system, often combined with the pathology of the organ of vision, the presence of diabetes insipidus, the preservation of gonadotropic functions, and changes in the intellect.
The expressed dormancy is accompanied by some kinds of dysgenesis and agenesis of the gonads, in particular Shereshevsky-Turner syndrome and the "turnaround" (mosaic) form of the testicular dysgenesis syndrome. Differential diagnostics is assisted by cytogenetic studies (sexual chromatin, karyotype) that detect chromosomal defects, as well as characteristic defects of somatic and sexual development, normal or elevated levels of endogenous growth hormone, and insensitivity to treatment with somatotropin.
Among endocrine disorders that occur with short stature, primary hypothyroidism due to congenital hypoplasia or aplasia of the thyroid gland, its dystopia, enzyme defects in the biosynthesis of thyroid hormones, early autoimmune thyroid disease is to be distinguished . For all these conditions, signs of hypothyroidism with a high level of TSH, a decrease in T 4 and T 3 in the blood serum dominate . With myxedem autoimmune genesis, antibodies to thyroglobulin, microsomal and nuclear fractions of thyroid tissue are detected in the blood, the level of normal growth hormone is normal or decreased. The clinical effect can be achieved only by compensating for hypothyroidism.
Low growth accompanied by premature sexual development and adrenogenital syndrome due to early closure of growth zones; Itenko-Cushing's disease, which arose in childhood due to the inhibitory effect of glucocorticoids on the secretion of growth hormone and their catabolic effect; Mauriac's syndrome is a short stature and infantilism of patients with insulin-dependent diabetes mellitus of severe form.
Gipofizarnyj nanizm it is necessary to differentiate with somatogenic delay of the physical development caused by chronic infringements of an exchange (at diseases of a liver, kidneys, a gastrointestinal tract), a chronic hypoxia (at diseases of cardiovascular and respiratory systems, at anemias); with systemic diseases of the musculoskeletal system (chondrodystrophy, imperfect osteogenesis, exostosis disease), etc.
Functional (constitutional) growth retardation is sometimes observed in the late onset of pubertal period in practically healthy adolescents; we found that it is primarily associated with transient insufficiency of gonadotropic activity. Secretion of growth hormone is usually not disturbed or reduced slightly. Stimulation of gonadotropins can cause acceleration of both sexual development and growth.
Low-growing family character should be considered as a variant of physiological development.
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