The term renal failure denotes inability of the kidneys to perform excretory function leading to retention of nitrogenous waste products from the blood. Functions of the kidney are as follows:
Acute and chronic renal failure are the two kinds of kidney failure.
Acute Renal Failure (ARF)
ARF is the syndrome in which glomerular filtration declines abruptly (hours to days) and is usually reversible. According to the KDIGO criteria in 2012, AKI can be diagnosed with any one of the following: (1) creatinine increase of 0.3 mg/dL in 48 hours, (2) creatinine increase to 1.5 times baseline within last 7 days, or (3) urine volume less than 0.5 mL/kg per hour for 6 hours.  Recently the term acute kidney injury (AKI) has replaced ARF because AKI denotes the entire clinical spectrum from a mild increase in serum creatinine to overt renal failure. 
Chronic Renal Failure (CRF)
CRF or chronic kidney disease (CKD) is defined as a persistent impairment of kidney function, in other words, abnormally elevated serum creatinine for more than 3 months or calculated glomerular filtration rate (GFR) less than 60 ml per minute / 1.73m2. It often involves a progressive loss of kidney function necessitating renal replacement therapy (dialysis or transplantation). When a patient needs renal replacement therapy, the condition is called end-stage renal disease (ESRD). 
CKD classified based on grade:
CKD classified based on stage:
Renal Failure Etiopathogenesis
Acute Renal Failure 
Chronic Renal Failure 
The incidence of AKI has been cited as 1% on hospital admission, 2% to 5% during hospitalization, and in as many as 37% of patients treated in intensive care units (ICUs), and in 4% to 15% of patients after cardiovascular surgery.   
Renal failure pathophysiology can be described by a sequence of events that happen while during acute insult in the setting of acute renal failure and also gradually over a period in cases of chronic kidney diseases.
Broadly, AKI can be classified into three groups: 
The pathophysiology of CRF is related mainly to specific initiating mechanisms. Over the course of time-adaptive physiology plays a role leading to compensatory hyperfiltration and hypertrophy of remaining viable nephrons. As insult continues, sub sequentially histopathologic changes occur which include distortion of glomerular architecture, abnormal podocyte function, and disruption of filtration leading to sclerosis. 
The relevant history and physical examination findings associated with renal failure include:
Patients with renal failure have a variety of different clinical presentations as explained in history and physical exam section. Many patients are asymptomatic and are incidentally found to have an elevated serum creatinine concentration, abnormal urine studies (such as proteinuria or microscopic hematuria), or abnormal radiologic imaging of the kidneys. The key laboratory and imaging studies to be ordered in patients with renal failure follow.
Fractional excretion of sodium (FENa) = [(UNa x PCr)/ (PNa x UCr)] x 100, where U is urine, P is plasma, Na is sodium, andCr is Creatinine. If FeNa less than 1, then likely prerenal; greater than 2, then likely intrarenal; greater than 4, then likely postrenal
If the patient is on diuretics, use FEurea instead of FENa. Complete blood count, BUN, creatinine (Cr), arterial blood gases (ABGs)
More advanced imaging techniques should be considered if initial tests do not reveal etiology:
Treatment options for renal failure vary widely and depend on the cause of failure. Broadly options are divided into two groups: treating the cause of renal failure in acute states versus replacing the renal function in acute or chronic situations and chronic conditions. Below is the summary of renal failure treatment.
Acute Renal Failure
Immediate Dialysis Indications
Chronic Renal Failure
The management of kidney failure is usually done with a multidisciplinary team of healthcare professionals dedicated to preserving renal function. Kidney failure has enormous morbidity and mortality, costing the healthcare system billions of dollars each year. Today most hospitals have a kidney failure nurse whose job is to educate patients on the causes, detection, and prevention of kidney failure. The pharmacist also needs to regularly audit patient medications for those that are nephrotoxic. When monitoring patients with kidney failure, the nurse should note the urine output, levels of potassium, blood sugar and creatinine. Control of blood pressure and blood sugars is vital in the prevention of kidney disease. The pharmacist should emphasize the importance of medication compliance for treatment of blood pressure. These patients should have close follow up to ensure that the renal function is not deteriorating. Finally, the patient needs to be given advice on healthy eating, exercise, discontinuing tobacco and abstaining from alcohol. Kidney disease is not well managed can lead to complete renal failure, which requires dialysis. (level V)
Recovery from acute renal failure depends on the cause of the disease. If the cause is reversible, the prognosis is good and leans toward a full recovery. Partial recovery of renal function may occur if the injury does not fully resolve. Severe cases of acute renal failure can result in death.
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