Another effect of 1,25-dihydroxycholecalciferol is that it promotes the formation of calcium-stimulating Ca 2+ H + -ATPase in the epithelium, which increases the transport of calcium into the blood.
Calcitriol also promotes the formation of adapen phosphatase in the epithelium. The final mechanisms have not been elucidated.
Effect of 1,25-dihydroxycholecalciferol on bone tissue. Calcitriol increases bone resorption and new formation. Osteoblasts have receptors in the cytoplasm for calcitriol. An increase in the rate of metabolic processes in the bones, stimulated by calcitriol, facilitates the exchange of calcium and phosphate reserves in the bones with the extracellular pool of these ions.
Mechanism of diicalcalcitriol (1,25-dihydroxycholecalciferol) on the intestinal epithelium. G - hormone, P - receptor.
Vitamin D deficiency leads to buy adapen online calcification of the bone matrix, which is called rickets in children and osteomalacia in adults. In children, there is weakness and bending of the supporting bones, dental defects, hypocalcemia. The effect of 1,25-dihydroxycholecalciferol on the kidneys. It promotes Ca 2+ reabsorption in the distal tubules of the nephron and HPO2- reabsorption in the proximal tubules.
Treatment of 21-hydroxylase deficiency.
The main method of therapy for 21-hydroxylase deficiency is the use of glucocorticoids, which suppress the hypersecretion of ACTH and normalize the production of androgens by the adrenal glands.
Various drugs with glucocorticoid activity are used. prednisolone, cortisone, dexamethasone. However, these synthetic cortisol analogues have a negative effect on growth processes, their prolonged effect can quickly lead to overdose symptoms. For children with open areas of growth, especially younger ones, the most optimal drugs should be considered tablet analogues of hydrocortisone (Cortef, Pharmacia). The initial daily dose of hydrocortisone required to suppress ACTH in children of the first year of life can reach 20-25 mg/m2.
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However, prolonged use of these doses in a child should be avoided. On average, in children older than 1 year, the daily dose of hydrocortisone should be 10-15 mg / m 2. The drug is given three times a day in equal doses. Higher doses of hydrocortisone lead to persistent growth retardation and other Cushingoid manifestations. In children with growth zones close to closure, prolonged glucocorticoid drugs should be used, which have a more pronounced ACTH-suppressing effect.
The daily dose of these drugs should correspond to an equivalent dose of hydrocortisone 10-15 mg/m 2 per day (prednisolone - 2-4 mg/m 2, dexamethasone - 0.25-0.35 mg/m 2). For maximum suppression of ACTH secretion, 1/3 of the daily dose of prednisolone is prescribed in the morning and 2/3 of the dose at bedtime (table 7).
Comparative characteristics of biological activity. Comparative Activity Hydrocortisone Cortisone Prednisolone Dexamethason Fludroxycortisone Time of biological activity Glucocorticoid 0.8 Mineralocorticoid 0.8 0.5 0.05 All children with salt-wasting 21-hydroxylase deficiency require additional mineralocorticoid preparations. Indications for the appointment of mineralocorticoid therapy are.
a high level of renin activity in blood plasma with a normal level of K + and the absence of clinical symptoms of salt loss.
The dose of fludroxycortisone (Cortinef) is 0.05-0.3 mg/day. Such therapy makes it possible to buy differin gel online for the lack of mineralocorticoids, to achieve more rapid suppression of excess ACTH secretion with the use of lower doses of glucocorticoids. The need for mineralocorticoids is maximum in children of the first year of life and is 0.1-0.3 mg per day. The daily dose is prescribed in three doses (at 7.00-15.00-23.00). Additionally, an excess amount of table salt is introduced into the diet - up to 2 g per day.
