term « tubulopathy » combined quite diverse clinical manifestations group of diseases, which are based on a violation of the processes of tubular transport (transport of substances in the renal tubules) reabsorption (reuptake) and secretion (urinary excretion) of various substances - protein,organic compounds.Most often it is a violation of reabsorption of the compounds of the glomerular apparatus of the kidneys in the formation of primary urine in them, as well as defects of tubular secretion.
primary reason (hereditary) tubulopathy may be associated with such defects tubules as:
1) changes in the molecular structure of the proteins that make up the epithelium of the renal tubules;
2) fermentopathy - hereditary deficiency of enzymes involved in the active transport of substances through the membrane of the renal tubules;
3) changes in the structure and function of the receptor apparatus tubule, which leads to lower sensitivity to hormones;
4) a change in the overall structure of tubular cells an
main clinical manifestations tubulopathy determined localization of the primary defect during the renal tubules.Structural and functional unit of the kidney is the nephron.It is arranged as follows: first, the renal glomerulus is formed by a dense network of capillaries;departs from the glomerulus proximal (closest to the glomerulus) convoluted tubule;followed by the loop of Henle, consisting of the downstream and upstream of the renal tubules;after it is distal convoluted tubule (distal to the glomerulus).The whole structure ends up collecting tubule, which flows into the renal pelvis.Through this whole system of tubes passes the primary urine, the volume of which can be up to 120 liters per day.
In all these tubules from the primary urine back into the blood absorbed water and various chemical substances such as a protein, sugar (glucose), potassium, sodium, chloride, phosphorus, leading eventually to the formation of the final urine.In this case, each of the tubular reabsorption occurs strictly defined substances, which determines the clinical picture in the defeat of any portion of the nephron.The proximal convoluted tubule is performed reabsorption (reuptake) of amino acids, glucose, inorganic phosphates, and therefore their loss is characterized by the appearance of the listed substances in the urine (giperaminoatsiduriey, glucosuria, giperfosfaturiya), as well as violation of the acid-base balance in the body, and it is happeningshift it to the acid side (marked metabolic acidosis).Full range of such disorders is characteristic of the disease and syndrome De Toni-Fanconi-Debre.In addition, defects may separate transport systems, which may occur either alone or phosphaturia of glucose (glucose in the urine or phosphorus, respectively), metabolic acidosis.The loop of Henle and distal convoluted tubules provide regulation of homeostasis - constancy of the ionic composition and the osmotic blood pressure and body fluids.There are carried out the processes of water-saving and emission of excess (secretion) of osmotically active substances, excess secretion of hydrogen and sodium ions, the economy or the secretion of potassium ions.Therefore, manifestations of defects of the distal nephron is mainly characterized by disorders of homeostasis - renal tubular acidosis, dehydration - the loss of body fluid (renal diabetes), loss of salt or hypokalemia (decrease in the amount of potassium in the blood).
Increased urinary excretion of organic and inorganic substances often due not only renal tubular lesion, but the common metabolic disorders in the body when the concentration of these substances in the blood and increases, respectively, glomerular ultrafiltrate (primary urine).Therefore, for the diagnosis of renal origin or homeostatic metabolic disorders is necessary to conduct the study of the corresponding compounds not only in urine but also in the blood plasma.
In addition, defects in transport systems can be identical in the kidney and intestine (though not always), so in the clinical setting special studies performed, allowing to establish the possibility of joint involvement in the pathological process of the transport systems of the intestine and kidney.