Tubulointerstitial diseases are clinically heterogeneous disorder with common characteristics of a tubular and interstitial damage. In severe and protracted cases, the entire kidney by glomerular dysfunction and even kidney failure can be affected. The primary categories of tubulointerstitial diseases are acute tubular necrosis or chronic tubulointerstitial nephritis, acute A contrast medium-induced nephropathy is an acute tubular necrosis, which is caused by an iodinated X-ray contrast agent. Analgesic, reflux nephropathy and myeloma kidney are forms of chronic tubulointerstitial nephritis. Tubulointerstitial disorders may also result from metabolic disorders and exposure to toxins. Pathophysiology The kidneys are exposed to unusually high concentrations of toxins. The kidneys of all tissues of the highest blood flow (about 1.25 ml / g / min or 25% of the heart volume). Unbound soluble substances leave the bloodstream by glomerular filtration at a rate of ? 100 ml / min, and resultantly toxic substances are 50 times faster and transported in a much higher concentration than in other tissues. By the urine concentration of the lumen-side surfaces of the tubular cells molecular concentrations are exposed that are 300-1000 times greater than that of the plasma. The fine brush border of proximal tubular cells form a large surface. The opposite direction flow mechanism increases the ion concentration in the interstitial fluid of the medulla up to four times the plasma concentration, leading to an increase of the urine concentration. In addition, factors can affect the cellular susceptibility to exposure to toxins: the tubular transport mechanism separates drugs from their protein binding, the cells normally protects against the toxicity. The transcellular transport exposed the interior of cells and their organelles again to these chemicals. The binding sites of some substances (eg. B. sulfhydryl groups) may facilitate penetration, but complicate the exit (z. B. heavy metals). Chemical reactions (alkalization, acidification) will alter the transport in both directions. By blocking receptors transport the tissue exposure can change (e.g., such as diuresis, by blocking the adenosine A1 receptor so as to reduce exposure Aminophylline). The kidneys have the highest oxygen – and glucose consumption per gram of tissue and are therefore to toxins that affect the energy metabolism of the cells vulnerable.


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