Acute renal failure, also known as acute kidney injury or Kidney injury – acute, is rapid sudden deterioration in the function of the kidney that develops within hours or days. Several causes can contribute to acute renal failure but reduced blood flow to the kidneys, kidney damage, and urinary tract obstruction are the main causes and are the outcomes of other diseases such as hypertension, liver and heart diseases, and others.

The risk of acute renal failure is increased in certain categories such as inpatients and diabetics, heart, kidney, liver, or hypertension patients, obese, old people and smokers. Symptoms that appear in patients with acute renal failure are decreased urine output, swelling in legs, ankles, and around the eyes as a result of fluid retention, nausea, fatigue, seizures and confusion to keep the list short.

There are different types of diagnostic tests to check for acute renal failure such as blood urea nitrogen, creatinine clearance, urinalysis, blood tests, and imaging tests.

The first step for treating acute renal failure involves determining the cause of the disease. This is essential because once the cause is treated the kidney problem will be solved. In severe cases dialysis; the mechanical filtration process used to remove toxins and wastes from the body, is needed to replace the kidney function. Diuretics are used to manage fluid retention.  Calcium, glucose or sodium polystyrene sulfonate are used to manage hyperkalemia, while the infusion of calcium is used to treat hypocalcemia.

Usually, acute renal failure lead to a number of complications, including fluid retention, chest pain, muscle weakness, permanent kidney damage, and death.

Acute renal failure can effectively be prevented by adapting healthy habits such as eating in a healthy way and consuming sufficient amounts of water, being cautious with over-the-counter (OTC) pain relief medications, decreasing exposure to nephrotoxic, and not ignoring other health problems such as diabetes, heart diseases, and liver diseases.

According to a study in an American journal, Comprehensive Physiology, in the developed world, acute renal failure has primarily become a nosocomial disease, which are infections that have been caught in a hospital and are potentially caused by organisms that are resistant to antibiotics. Acute renal failure has an incidence of 5–7% in hospitalized patients.

Acute renal failure is a sudden damage of the kidney that progresses rapidly within a few hours or a few days. This makes the kidney unable to filter and excrete wastes from the blood, outside the body. This leads to the accumulation of hazardous waste products.

Several factors can lead to acute renal failure such as:

• Reduced blood flow to the kidneys

The blood flow to the kidneys is slowed down by certain health conditions and diseases to the kidney and cause acute renal failure such as:

• Hypotension which is low blood pressure.
• Blood or fluid loss such as severe dehydration.
• Heart diseases including heart attack, heart failure, and other conditions which affect the functions of the heart.   
• Organ failure such as liver, and injury.
• Infections.
• Severe burns.
• Severe allergic reaction (anaphylaxis).
• Overdose of NSAIDs medications that relieve pain or reduce swelling such as ibuprofen, ketoprofen, and naproxen.
• Major surgery.

• Kidney damage

Kidneys can be damaged by certain health conditions and diseases causing acute renal failure such as:

• Presence of blood clots inside kidney arteries veins.
• Presence of cholesterol deposits which can prevent blood from flowing in the kidney.
• Glomerulonephritis; inflammation of glomeruli which are tiny filters in the kidneys, and any other disease that causes inflammation or damage to the kidney tubules, to the small blood vessels in the kidneys, or to the filtering units in the kidneys.
• Hemolytic uremic syndrome which happens when red blood cells are destroyed earlier than usual.
• Lupus, an immune system disorder responsible for glomerulonephritis.
• Certain medications such as some types of chemotherapy drugs, antibiotics, dyes used during imaging tests, and zoledronic acid which is a drug used to treat osteoporosis and hypercalcemia which is high blood calcium levels.
• Infection.
• Multiple myeloma which is identified as cancer of the plasma cells.
• A group of rare diseases called scleroderma which affects the skin and connective tissues that support the internal organs.
• A rare type of blood disorder called thrombotic thrombocytopenic purpura which is clotting in small blood vessels of the body that leads to low platelet count.
• Sepsis, which is a type of severe life-threatening infection.
• Vasculitis, it is a rare disease that causes inflammation and scarring to the blood vessels, making them stiff, weak, and narrow.
• Interstitial nephritis, which is an allergic reaction to certain types of drugs.
• Exposure to certain toxins such as alcohol, heavy metals and cocaine.

• Urinary tract obstruction

Certain types of diseases can obstruct the passage of urine out of the body, causing acute renal failure such as:

• Cancers of the bladder, prostate, or cervix.
• Enlarged prostate.
• Kidney stones.
• Damage of the nerves responsible for controlling the bladder and urination.

Acute renal failure related risk factors may include:

• Being hospitalized, which poses a higher threat in the case of a serious condition that requires intensive care.
• Older age.
• Peripheral artery disease, which involves a blockage in the blood vessels of the arms or legs.
• Diabetes.
• Obesity with a body mass index (BMI) of 30 or higher.
• Hypertension, which is high blood pressure.
• Preexisting heart diseases such as heart failure, heart attack, and stroke.
• Kidney diseases.
• Liver diseases.
• Family history with kidney failure.
• Smoking.
• History of acute kidney injury.

• Generally, acute renal failure is known as sudden occurrence of oliguria; which is a less than usual urine output that indicates renal failure, or anuria; absence or defective excretion of urine, with an increment of K+ and H+ ions, creatinine, and urea in the plasma concentrations. 80% of acute renal failure is due to hemodynamic crisis (shock) which is circulatory failure that results in inadequate cellular oxygen utilization.
• Anuria happens because of filtration failure as a result of decreased renal circulation, during circulatory shock. The early stage involves a decrement in the pressure of an effective glomerular filtration, which is the first step in making urine as a consequence of renal vasoconstriction, which is known as narrowing of the blood vessels that results in slowed or blocked blood flow, by increased activity of renal sympathetic nerve and by increased concentration of circulating catecholamines, which includes epinephrine, and norepinephrine, secreted from the adrenal medulla, during “fight-or-flight response”, as well as reduced systemic pressure; blood pressure in the main arteries of the body, beginning from the heart’s left side and running through the entire body

Symptoms of acute renal failure include the following:

• The normal output for urine is sustained sometimes, but in most cases it becomes decreased.
• Fluids are trapped inside the body, causing swelling in legs, ankles, and around the eyes.
• Shortness of breath.
• Nausea.
• Fatigue.
• Severe cases could be accompanied by seizures or coma.
• Pain or feeling pressure in the chest.
• Confusion.
• Drowsiness.

Some cases of acute renal failure may show no symptoms, which can be detected through other tests that are done for other reasons.

Based on previous identification of signs and symptoms, these tests are recommended for diagnosis:

• Blood Urea Nitrogen (BUN)

A sample for blood is analyzed for the quantity of urea nitrogen. BUN test is used to evaluate kidney function.

• Creatinine clearance

Creatinine levels are compared in both blood and urine which gives an indication of the proper functioning of the kidneys.

•  Urinalysis

Physical, chemical, and microscopic examination for urine are done, in order to measure various compounds that pass through the urine.

• Blood tests

Three tests provide an evaluation for the kidney function which are measuring creatinine, urea nitrogen phosphorus and potassium serum levels.

• Imaging tests

Ultrasound and computerized tomography (CT), for example, provide a detailed view for the kidneys which may be helpful in determining any abnormalities in the kidney.

• Kidney biopsy

Using a needle that passes through the skin and into the kidney tissues to obtain a small sample of kidney tissue to be tested in the lab.

• Glomerular filtration rate (GFR)

This test is able to reveal both the deterioration in kidney functionality and the stage of disease progression.

 The majority of acute renal failure patients are already hospitalized for another reason, by which hospitalization is required for treatment.  The cause and rate of responsiveness determine the length needed to be hospitalized.

Dialysis; the mechanical filtration process used to remove toxins and wastes from the body, may be introduced into treatment in order to help severe cases replace kidney function until the kidneys recover.

Treatments for acute renal failure involve:  

• Treating the direct cause that lead to the disease

The origin of illness or injury should be determined so that treatment can begin.

• Treat acute renal failure symptoms and complications

• Medications for fluid retention

Intravenous (IV) fluids are used if acute kidney failure is a result of the lack of body fluid. Diuretics are recommended for fluid retention to get rid of extra fluids that cause swelling in arms and legs.

• Medications for hyperkalemia

Calcium, glucose or sodium polystyrene sulfonate are given to stop the buildup of high levels of potassium in the blood. Because kidneys are not properly filtering potassium from the blood, hyperkalemia can cause arrhythmias (irregular heartbeats) and muscle weakness.

• Medications for hypocalcaemia

Infusion of calcium is given in case of decreased calcium levels in the blood.

Acute renal failure is often associated with several complications including:

• Fluid retention

Fluid accumulation in lungs may result from acute renal failure, causing shortness of breath.  

• Chest pain

Chest pain is a result of inflammation of the pericardium; the lining which covers the heart. 

• Muscle weakness

Muscle weakness is a result of fluid and electrolytes imbalance. Hyperkalemia can cause a serious problem.

• Permanent kidney damage

Sometimes, acute renal failure causes permanent loss of kidney function, or end-stage renal disease. End-stage requires long term dialysis or kidney transplant.

• Death

Frequent occurrence of acute renal failure or other kidney problems increase the risk of loss of kidney function and, eventually, death.

Key elements in preventing acute renal failure include:

• Getting sufficient hydration.
• Manage other health problems such as diabetes, heart diseases, and liver diseases.
• Keeping away from drugs that can cause acute renal failure and take into consideration the recommended doses for over-the-counter (OTC) pain relief medications, which is particularly important in the case of pre-existing kidney disease, diabetes or high blood pressure.
• Control kidney problems.
• Maintain a healthy lifestyle and keep body weight within its normal range.
• Reduce exposure to nephrotoxic.
•  Maintaining mean arterial pressure, which is mainly regulated blood pressure.

Acute renal failure is a critical disease that can cause mortality, regardless of treatment in some cases. In most cases, the patient recovers fully if the cause of acute renal failure does not harm the kidney tissue itself.

Age and comorbidity which is the simultaneous presence of two chronic diseases or conditions in a patient, negatively affect the prognosis of acute renal failure.

According to a study in an American journal, Comprehensive Physiology, in the developed world, acute renal failure has primarily become a nosocomial disease, which are infections that have been caught in a hospital and are potentially caused by organisms that are resistant to antibiotics. Acute renal failure has an incidence of 5–7% in hospitalized patients. This incidence seems to be increasing over time.