Acute Kidney Failure1. Explain the pathophysiology of acute renal failure. Include prerenal, intrarenal, and postrenal causes. Acute kidney failure occurs when the kidneys suddenly are unable to filter the blood of waste products. Acute kidney failure is alternatively called acute renal failure or acute kidney injury. The causes of acute renal failure are divided into three categories based on their point of origin: prerenal, intrarenal, and postrenal. The most common type of acute kidney failure is prerenal failure, which can be described as a sudden drop in blood pressure or interruption of blood flow to the kidneys. The most common causes of prerenal AFR include hypovolemia, reduced renal perfusion, and septic shock. “Prerenal AFR is generally reversible when renal perfusion pressure is restored” (Liu, p. 98). Acute intrarenal, or intrinsic, renal failure is caused by acute tubular necrosis, renal artery obstruction, renal vein obstruction, interstitial nephritis, and glomerulonephritis. The postrenal occurs between the kidney and the urethral meatus. The main causes of postrenal AFR are tubular precipitation, urethral obstruction, and bladder obstruction. Acute renal failure has four phases: onset, oliguria, diuresis, and recovery. Onset begins with the onset of the event and lasts from hours to days. The oliguria phase does not always occur in some patients, however it lasts 8-15 days. Oliguria deals with multiple diseases of the acid-base balance. The diuresis phase begins when the kidneys begin to recover and can last approximately 2-6 weeks. Finally the recovery phase continues until the kidneys have fully recovered. This could last up to two years.2. What diagnostic tests would be used to diagnose acute renal failure? How do these tests influence end-stage renal disease outcomes in the ICU? Kidney International,62(3), 986-96. doi: http://dx.doi.org/10.1046/j.1523-1755.2002.00509.xHealthwise Staff. "Acute prerenal renal failure". WebMD. WebMD, May 10, 2011. Web. December 04, 2013. Knippa, A. (2011). Nephritic syndrome and acute and chronic renal failure. PN Adult Medical-Surgical Nursing Review Form (8.0 ed., pp.624-635). Sitwell, KS: Assessment Technologies Institute. Liu Kathleen D, Chertow Glenn M (2008). Acute renal failure. In A. S. Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 2, pp. 1752-1761. New York: McGraw-Hill. 2008. 04 December 2013Salifu, Moro O. "Azotemia Workup". Work on azotemia. Medscape, June 15, 2012. Web. December 04, 2013.Tiu, A. Kidney disease. HRSA HIV/AIDS Programs. December 4, 2013 http://hab.hrsa.gov/deliverhivaidscare/clinicalguide11/cg-605_renal_disease.html