Acute renal failure (in Latin: Insufficientia renalis acuta) is a sudden, rapid and often reversible loss of renal function.
It may be due to hypovolemia (dehydration, low blood pressure, acute hemorrhage, and circulatory shock), adoption of kidney-toxic substances (kidney poisons), systemic or localized to the urinary tract infection or obstruction of the urinary tract. This differs from chronic renal failure, primarily in the evolution of the disease and in the reversible course of the acute form. People with renal failure present a number of non-specific symptoms which must be ordered by significance. Abrupt increase in body weight within days or a week or two, without deliberate eating, decreased volume and frequency of urinating, backache, backache, nausea when taking water and other liquids, slow heartbeat or palpitations, pant, chest pain, embarrassment seizures and other neurological symptoms. Treatment of acute renal failure can be successful if it is diagnosed in time and a reversible mechanism is discovered, for example when toxins are taken – to be antagonized with antidote. In general terms acute renal failure is treated through correcting humoral balance, identifying and removing the outer aggression, for example medicines taken with nephrotoxic effect, as well as initiation of antibiotic treatment of bacterial diseases. The combination of diuresis and rehydration with proper intravenous is effective for the light form of the condition. For severe forms of acute failure, a temporary hemodialysis may be necessary.

Epidemiology

According to the US statistics, till the year 2000 ARF was discovered in about 5% of the hospitalized patients. In USA about 0.5% and 15% of these cases need hemodialysis. According to a research made in Canada among 4066 hospitalized patients who survived ARF, on average 2.63% of the cases of acute failure, compared to 0.91% of the total population, pass into the chronic disease with the need for dialysis or transplantation. The death rate of patients with ARF varies from 45 to 70% preliminary because of the fact that many of them are with welded history of serious diseases, often at intensive hospital treatment with aggressive therapies and ARF is a consequence of the other treatments. Patients with ARF, who require hemodialysis and are on controlled respiration, have longer convalescence period, more uncertain resuscitation and higher mortality as the relative risk may be with 51% higher than the common population.

Common criteria

There is a range of definitions of ARF. According to the circumstances and existing treatments, some sources indicate more liberal and others more conservative parameters of ARF. Most experts speak of ARF in raising serum creatinine 0.5 mg / dL at baseline 1.9 mg / dL.
The classification Risk-Damage-Failure/Loss-Terminal phase is useful. It treats the acuteness of the condition based on the excreted urine and the glomeruli filtration index and it is valid in clinical circumstances for predicting the likely outcome of the current ARF.

Classification according to the locus of reason

Acute renal failure can be classified according to the location and mechanism of reasons, addressing three main ways:
(1) disorders occurring due ti causes giving rise to structures and systems conventionally “before” the kidney (i.e. before the process of filtration),
(2) inside the kidney structures (from Bowman capsule to the urethra) and
(3) after kidney – from ureter (ureters) to exit from the urethra (the urethra).
There are several mechanisms that may affect any or all parts of the urinary process. For example, traumatic breach of the functions of the system can cause problems not only with blood flow (due to a fall in blood pressure and shock), but also in the internal integrity of the body (kidney injury) or excretory pathways (tearing, pinching, or obstruction of urinary tract, bladder and urethra). Problems within the kidneys can be caused by an allergic or toxic reaction to drugs or food or actual “poison”. Acute conditions of dehydration (drying) can concentrate urine under the effect of anti-diuretic hormone, which activates the reabsorption of water after filtration, but in extremes can suspend temporarily or permanently urine output. Persons with kidney stones or very enlarged prostate can suffer from congestion of the urethra, and in the first case the ureter; and this causes the retention and return of urine into the kidney and causes kidney swelling (hydronephrosis). For these reasons, ARF is classified as pre-renal, internal (intra-renal) and post-renal.

Pre-renal

Pre-renal causes of ARF (“pre-renal azotemia”) are generally those that reduce the blood supply to kidney. Among them rank systemic reasons as already mentioned hypovolemia, hypotension, heart failure and localized pressure fluctuations in the renal arteries. These include renal artery stenosis supplying the kidney with blood, thrombosis of renal vein draining blood filtered by the kidney, local puncture or tear injury affecting vessels, renal artery vasospasm and others.

Intra-renal ARF

Intra-renal ARF is characterized by local tissue or organ damage or imbalance of processes, the most common causes are consumed or produced in the kidney toxins or perhaps some local inflammatory damage leading to lack of oxygen in the kidney as a whole and particularly in the nephrons. Whether it ischemia or cytotoxicity in both, the offense is a cell renal tissue local level, rather than for reasons outside (before or after) the kidney. As a result, any of the possible mechanisms that cause ischemia or cytotoxicity leads to acute tubular necrosis and expansion of possibly irreversible ischemic changes in the kidney.