The sharp decrease of urine may represent functional adaptation, but most often an expression of a serious health problem.
This health problem is called “acute renal failure” and is accompanied by death in around 80% in critically ill patients.
Oliguria (urine output below 400 ml / day) may not be associated with renal impairment and is due to increased secretion of antidiuretic hormone.
Abnormal renal function and when we think:
- There is an increase in serum creatinine of more than 50% from baseline over 1-3 days
- There is a reduction in creatinine clearance by 50%
- Tezhkostepenna renal dysfunction requiring replacement therapy
The above criteria help identify acute renal failure, which is traditionally separated into 3 categories depending on the localization of anatomical problem responsible for oligoanuriyata.
Prerenalnite sources of acute renal failure (ARF) are located proximal to the kidneys and are characterized by reduced blood flow renovascular. Diseases in this category include: hypovolemic, cardiogenic shock (a severe cardiac dysfunction), loss of vascular tone, medications that promote renal vazakonstriktsiya (NSAID), and drugs that reduce glomerular filtration pressure (ACE inhibitors). Prerenalnite diseases are responsible for about half of the cases with PROM.
They engagement renal parenchyma and are characterized by impaired glomerular filtration, tubular dysfunction, or both. Most often it is a one of the following three conditions: acute glomerulonephritis, acute tubular necrosis or acute interstitial nephritis. Acute tubular necrosis is the most common cause of renal ARF, most happy are her etoilogichni reasons are: sepsis, circulatory shock or nephrotoxin. Toxins include drugs (aminoglycosides) radiokontrastni agents and pigments (mioglobulin).
Acute tubular necrosis (RE)
PROM is arakterizira mostly ineffective filtration through the glomeruli, however at RE pathological affect not affect the glomeruli, but affects the renal tubules and surrounding parinhim. The most commonly affected and proximal tubes that are filled with tubular epithelial cells, which create obstruction is ritrogradno increase intratubilnoto pressure, leading to a decrease and the net filtration pressure across the glomerular capillaries.
Impaired renal tubes are supposed to be due to ischaemia or inflammation and if this process is spread in other organs in the body develops t.nar.sindrom of multiorgan dysfunction. In this case intarenalnata renal failure is part of an overall pathological process rather than localized disease.
In postrenalnite diseases causing PROM obstruction is distal to the renal parenchyma. Diseases in this category include: (1) obstruction of the collecting system (papillary necrosis); (2) The ureters (retroperitoneal tumors) and (3) the bladder (stricture prostatism).
The initial study of a patient with ARF should begin with microscopic and, if necessary, a chemical analysis of urine.
The differential diagnosis of renal failure based on findings in urine is given in a separate article on the site.