Hypopituitarism in children - symptoms, signs, diagnosis and treatment
Hypopituitarism in children - symptoms, signs, diagnosis and treatment
Hypopituitarism in children, which is the cause of short stature
(Pituitary Nanism) Decreased pituitary function in childhood causes typical abnormalities that lead to slower growth with normal body proportions. As a rule, this condition is a consequence of the development of a pituitary tumor, but it can also develop idiopathically. Diagnosis includes determining the levels of growth hormone in the serum: basal and in response to pharmacological stimulation. Treatment usually involves the surgical removal of the tumor that caused the pathology and the administration of GH replacement therapy.
Hypopituitarism in children can be generalized, including a deficiency of several pituitary hormones, but usually the primary and most prominent clinical manifestation is shortness due to a deficiency of GH.An isolated deficiency of GH may also occur.
Reduction of pituitary function in children, usually develops as a result of tumor growth (most often cranio-pharyngioma) or is idiopathic. The combination of several factors: lytic bone damage of the skeleton or skull and the presence of non-diabetes mellitus - suggest granulomatosis of Langerhans cells. Both hypothalamic or pituitary and isolated GH deficiencies can occur in patients with congenital medial defects of the facial skull, such as cleft palate or septooptic dysplasia, including septum pellucidum atresia, atrophy of the optic nerve and hypopituitarism. GH deficiency, either isolated or developing in patients with other pathologies, is a hereditary disease and occurs in approximately 5% of cases.
Therapeutic irradiation of the CNS, used in the treatment of a number of tumors, leads to a slowdown in the linear growth of the bones of the axial skeleton, which can often lead to GH deficiency. Radiotherapy of the spinal cord (either prophylactically or with a therapeutic purpose) can lead to a further potential disruption of the growth of the vertebrae and thus the further progression of short stature.
Symptoms, signs and diagnosis
In a child with hypopituitarism, growth is below the 3rd percentile, and the growth rate is less than 6 cm / year to 4 years of age, less than 5 cm / year between 4 and 8 years old and less than 4 cm / year in puberty. The maturity of the bones of the skeleton, estimated by the method of determining the bone age, shows that the biological bone age is more than 2 years behind the passport.
Despite their small stature, children with hypopituitarism remain normal proportions between the upper and lower parts of the body. The child does not begin puberty in puberty. However, a child with isolated secondary GH deficiency may have delayed sexual development.
Data on the height and weight of all children should be regularly applied to the somatogram — a special growth chart (auxological dynamic observation). If, as a result of the analysis of the somatogram, growth disorders are found, it is imperative to investigate the bone age using X-ray of the left hand (in accordance with the accepted agreement). With the development of GH deficiency, the biological bone age usually lags behind the passport age.Examination of the pituitary gland and the region of the Turkish saddle with CT and MRI is prescribed to detect calcification and tumor growth; 10–20% of patients show a Turkish saddle of pathologically small size.
In the pre-pubertal period, the level of insulin-like growth factor 1 (IGF-1) is measured, which reflects the activity of GH, since the level of GH itself is too variable and its value is often difficult to interpret. Normal IGF-1 values help eliminate GH deficiency. Nevertheless, there have been cases of a decrease in IGF-1 levels in conditions other than GH deficiency, such as psychosocial isolation, malnutrition, and hypothyroidism, for example. Since in adolescents and in the period of younger children—Since the levels of IGF-1 are usually located at the lower limit of normal values, they do not allow to determine with sufficient accuracy the difference between normal and pathological conditions. Therefore, in children of these age groups, levels of IGF-binding protein of type 3 (IASB-3 - the main carrier of IGF-proteins) are measured. The level of IFRS-3 is less affected by malnutrition (protein starvation) than by the level of IGF-1.
In children with reduced levels of IGF-1 and IFRSB-3, GH deficiency is usually confirmed by measuring GH levels.Due to the fact that basal GH levels are usually extremely low or even not determined (except when the patient is taken in a dream), the study of GH levels requires the use of provocative samples. However, provocative tests are not physiological; laboratory artifacts often occur, and, in addition, there are tests that are difficult to reproduce in clinical practice, so you can not rely on the correct interpretation of the results, since the very concept of "norm" very strongly depends on the age and sex of the patient.
In this regard, the test for tolerance to insulin may be the most effective of all stimulation tests for the isolation of GH. Tests using arginine infusion (500 mg / kg intravenously, over 30 min), levodopa (500 mg / kg orally to adults, 10 mg / kg to children), sleep or 20 are less dangerous for the test, but also less reliable in the diagnostic plan. minutes of intense exercise. Clonidine (4 mg / kg orally) is also a potential stimulant of GH secretion, promising to become an alternative to insulin. Side effects are insomnia and a slight drop in blood pressure.Usually any level of GH is greater than 10 ng / ml or any response to stimulation greater than 5 ng / ml after the sample is sufficient to eliminate the GR deficiency. Increasing the level of GH by 5-10 ng / ml and less is very difficult to interpret.
Which of the results obtained in response to stimulation is taken for a normal response, nevertheless is solved by the researcher arbitrarily, therefore the results of all stimulation samples of GH secretion are sometimes misleading. Due to the fact that none of the selected tests are effective in 100% of cases for proving the release of GH, a second pharmacological stimulation should be performed if the first one does not give a positive result. The peak of the level of GH is usually observed 30–0 minutes after the administration of insulin or immediately after the administration of arginine; at 30–0 minute after administration of levodoop; 60—0 minute after waking from sleep or clonidine and after 20 minutes of intense physical exertion. Because the response to stimulation of GH is usually difficult to interpret in patients with reduced thyroid function and adrenal glands, samples in this group of patients should be performed only after adequate replacement therapy.
The role of exogenous rilling factor GH (RFGR) in the evaluation of GH secretion is not established.In healthy people, a dose of 1 µg / kg of intravenous administration of RFGR in a jet for 15–30 seconds leads to a maximum, but highly variable release of GH, usually the peak of blood concentration is reached about 60 minutes after the injection. The large variability of results in response to stimulation of the pituitary RFGR is part of the hypothesis that the uneven secretion of somatostatin, which is contrasted with the RFGR, is a response to a decrease in secretion by the pituitary GH at the outlet. Presumably, the absence or reduction of an increase in GH secretion in response to stimulation of RFGR helps to identify patients with GH deficiency, but it is not clear whether this serves as a criterion for the differential diagnosis of primary hypothalamic disorder from pituitary diseases. In children with GH deficiency, presumably secondary, caused by a deficit of RFGR, there is a too variable response of GH to RFGR stimulation.
Provocative tests may not reveal subtle defects in the regulation of GH secretion. For example, in children with low growth, secondary to GH secretory dysfunction, the result of a provocative test for GH release is usually not different from the norm.Nevertheless, several consecutive measurements of levels of GH over a period of up to 24 hours reveal a violation in the form of a decrease in GH secretion at -m or 24th hour. If a decrease in GH secretion is confirmed, the secretion of other pituitary hormones or (if it differs from the norm) hormones of other peripheral endocrine glands must be assessed.
Treatment of hypopituitarism in children
All children with short stature with a documented deficiency of GH are given recombinant GH. The dose usually ranges from 0.03 to 0.05 mg / kg of body weight, subcutaneously, once a day. With the treatment, the growth rate often increases to 10– cm / year during the first year; although the intensity of this increase from this time decreases, yet it remains at a level greater than before the treatment. Therapy continues until a given growth is achieved or until the growth rate falls below 2.5 cm / year.
There are several side effects of GH therapy; they include idiopathic intracranial hypertension (pseudotumor of the brain), slipping of the femoral epiphysis (omission), and slightly pronounced transient peripheral edema.Before the advent of recombinant GH, a GH derived from the pituitary gland was used. The use of such GH could sometimes lead to the development of Creutz-Feldt-Jakob disease 20-40 years after treatment. The last time in clinical practice, GR, obtained from the pituitary gland, was used in the 80s.
At present, the question of whether it is worth treating children with clinical signs of GH deficiency, but its normal secretion and normal IGF-1 levels, should be treated with GH. Many experts recommend treatment of GH lasting from 6 to months, continuing it only if the growth rate doubles or increases more than 3 cm / year as compared to that before the start of therapy. Other approaches to the treatment of GH, because of their high cost, are experimental, can cause side effects, change the attitude of the public to other healthy children of not very high growth as in need of medical care and increase the ethical and psychosocial concern of society towards people of unusually low growth, shaping false beliefs of the society that strengthening nutrition can increase growth.
Lack of cortisol and thyroid hormones must be replenished during the entire period of childhood, adolescence, and adulthood in patients with short stature, caused by hypophysis-related stretching, when low levels of the corresponding hormones are found in the blood. In case of delay in sexual development, therapy with sex hormones is prescribed.
Therapy for GH in children with short stature, the cause of which is irradiation of the pituitary gland for therapeutic purposes in the treatment of tumors, carries the theoretical risk of progression of tumor growth. Nevertheless, the results of scientific research in this area have not shown the occurrence of a more expected case of recurrent tumor growth. Replacement therapy of GH, apparently, can be used in the complex treatment of patients with great care at least one year after the behavior of a successful radiation therapy.
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