Causes of Acute Renal Failure and Their Treatments

Treatment for acute renal failure (ARF), or acute kidney failure, involves various medications and procedures depending on the cause. With this condition, your kidneys are damaged and unable to filter waste from your blood.

Your treatment may include vasopressor drugs to help raise blood pressure, intravenous fluids to aid in rehydration, and diuretics to increase urine output. Hemodialysis may be used to help filter the blood while the kidneys are healing.

The course of treatment is directed by the underlying cause, which is broadly classified into one of three groups:

• Prerenal ARF, in which the blood flow to the kidneys is impeded
• Intrinsic ARF, in which the kidneys themselves are impaired
• Postrenal ARF, in which the flow of urine out of the body is obstructed

This article discusses the different causes of acute renal failure and the treatments available for each.

Prerenal ARF Treatment

For prerenal ARF to occur, both kidneys would need to be affected. There are several common reasons for blood flow to the kidneys to be impeded. These include dehydration, low blood pressure, congestive heart failure, and liver cirrhosis.

The aim of the treatment would be to restore the blood flow. There are several ways a healthcare provider might do this.

Dehydration and Low Blood Pressure

Dehydration leads to less water in the body and therefore reduces your blood volume. It may be treated with intravenous fluids at the hospital. The infusion of fluids would be monitored with a central venous catheter (CVC) to ensure that you don't get too much or too little fluid.

Dehydration can also cause blood pressure to drop because of the decrease in blood volume. If your low blood pressure persists despite intravenous fluids, vasopressor drugs may be used to raise the blood pressure.

Norepinephrine is a common option. Injected into the blood, the hormone causes blood vessels to contract, increasing the blood pressure. Side effects include headache, slowed heart rate, and anxiety.

Congestive Heart Failure

Congestive heart failure (CHF) occurs when the heart is unable to pump sufficiently to maintain the blood flow needed by the body. When this happens, it can lead to a state known as cardiorenal syndrome (CRS).

CRS is actually a two-way street. The lack of blood flow from the heart can affect kidney function. The failure of the kidneys can, in turn, lead to the impairment of the heart.

When the kidneys are affected, diuretics are commonly used to increase the output of urine and aid in the excretion of toxins from the body. Lasix (furosemide) is the most commonly prescribed diuretic, but it needs to be managed to prevent drug resistance.

In addition, the combined use of ACE inhibitors (commonly used to treat high blood pressure) and statin drugs (used to reduce cholesterol) may help normalize kidney function.

There may be a slight deterioration in kidney function over the short term. However, the continued, combined use of an ACE inhibitor and statin will ultimately have a protective effect on the kidneys.

Commonly prescribed ACE inhibitors include Capoten (captopril), Lotensin (benazepril), and Vasotec (enalapril). Commonly prescribed statins include Crestor (rosuvastatin), Lipitor (atorvastatin), Pravachol (pravastatin), and Zocor (simvastatin).

Liver Cirrhosis

Cirrhosis is the state in which the progressive scarring of the liver leads to liver damage. Cirrhosis can either be compensated, meaning the liver is still functioning, or decompensated, meaning that it is not.

ARF most commonly occurs when the liver is not functioning. It results in hepatorenal syndrome (HRS), which is a name for liver disease that leads to kidney disease.

In the absence of a transplant, your healthcare provider may recommend other interim approaches. Among them:

• Transjugular intrahepatic portosystemic shunt (TIPS) is a procedure in which an artificial channel is created in the liver using a wire mesh stent. This reduces the vascular pressure within the liver. This, in turn, alleviates the burden on the kidneys.
• Hemodialysis (popularly referred to as dialysis) involves the mechanical filtering of blood to effectively take over the function of the kidneys.
• Liver dialysis is a newer form of mechanical detoxification still in its infancy that, unlike hemodialysis, cannot be used for an extended period of time.
• Vasopressor drugs like midodrine, ornipressin, and terlipressin may help normalize vascular pressure in people with HRS. However, it may also adversely restrict the blood flow to the heart and other organs. The combined use of the vasopressor midodrine and the hormone Sandostatin (octreotide) may increase survival times in people awaiting a donor liver.

Intrinsic ARF Treatment

There are many reasons why a kidney may not function normally, including trauma, infection, toxins, vascular diseases, cancer, autoimmune disorders, and even complications of surgery.

These factors will typically result in one of three conditions:

• Glomerulonephritis (GN)
• Acute tubular necrosis (ATN)
• Acute interstitial nephritis (AIN)

Glomerulonephritis

Glomerulonephritis (GN) is the acute inflammation of the kidneys that develops in response to a primary disease. The diseases may include chronic illnesses like diabetes, autoimmune ones like lupus, or even an infection like strep throat.

Treatment depends on the underlying cause and may include:

• Termination of the suspected drug if the cause is believed to be drug-related
• Corticosteroids, synthetic hormones that can suppress the overall immune response and alleviate inflammation
• Lasix, a diuretic to increase urine output taken with a calcium supplement to prevent excessive calcium loss
• Potassium-reducing drugs like Kayexalate (sodium polystyrene sulfonate) to prevent hyperkalemia (high potassium), which is common with GN
• Plasmapheresis, a procedure in which your plasma (the fluid part of your blood) is removed and replaced with fluids or donated plasma that do not contain inflammatory proteins
• The restriction of protein, salt, and potassium from your diet, especially if the GN is chronic

Acute Tubular Necrosis

Acute tubular necrosis (ATN) is a condition in which the tubules of the kidney begin to die from a lack of oxygen. Common causes include low blood pressure and nephrotoxic drugs (drugs toxic to the kidneys).

Many of the same approaches used for GN will be applied here, including:

• Termination of suspected nephrotoxic drug
• Lasix
• Vasopressor medications
• Potassium-reducing drugs
• Restriction of protein, salt, and potassium
• Hemodialysis in severe cases

Acute Interstitial Nephritis

Acute interstitial nephritis (AIN) is the swelling of the tissue between the kidney tubules, often caused by a drug allergy or autoimmune disease.

Of the autoimmune causes, lupus (a disease in which the immune system may attack its own kidney tissues) is the most common. Some infections can cause AIN, as well.

Treatment of AIN is primarily focused on stopping the use of the suspected drug and restricting potassium, salt, and protein during recovery. Corticosteroids appear to provide little relief but may be used if stopping the drug doesn't restore normal kidney function.

Postrenal ARF Treatment

Postrenal ARF is caused by an obstruction of the urinary tract, which includes the kidneys, bladder, prostate, and urethra. Common causes include an enlarged prostate, kidney stones, bladder stones, or cancer of the kidneys, bladder, or prostate.

The goal of treatment would be to normalize the urine flow while the underlying cause of the impairment is investigated.

This may involve:

• A urinary catheter or stent to reroute the urinary flow around the obstruction
• Cystoscopy/ureteral stent, which is a small temporary straw to remove hydronephrosis (dilation of kidney/ureter) and relieve blockage caused by kidney stones, ureteral strictures, or external compression of the ureter
• Nephrostomy tube: Drainage tube inserted from your back directly into your kidney to maximize kidney drainage. This tube is usually temporarily placed in emergency settings until the cause of blockage or renal failure if found.
• Ureteroscopy/laser lithotripsy for renal or ureteral stones that are causing obstruction
• Cystolitholapaxy for bladder stones that are causing obstruction
• Prostate resection to open up the prostate channel to improve bladder drainage
  

Most people will regain normal kidney function if the condition is promptly reversed. If left untreated, the excessive pressure exerted on the kidneys, as well as the build-up of waste, can lead to kidney damage, sometimes permanent.

Summary

Treatment for acute renal failure depends on the cause. It may be due to something blocking blood flow to the kidneys, a problem with the kidneys themselves, or obstruction of the urinary tract.

Treatments may help to increase blood flow, rid the body of toxins, and manage the underlying condition. In some cases, hemodialysis may be needed to take over the kidneys' job of filtering blood.