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Urinary system: Renal failure



Content Reviewers:

Lisa Miklush, PhD, RNC, CNS

Renal failure happens when the kidneys don’t function at all or function at a low capacity, meaning that they are unable to filter blood properly.

As a result, a lot of waste products along with fluid build up in the body, affecting other organs in the body including the heart. In kidney failure, the individual can become very sick very quickly, especially if treatment is delayed.

There are two types of renal failure: acute and chronic. Acute renal failure, or acute kidney injury, happens when there’s a sudden loss of kidney function.

One cause of acute kidney injury is when there’s a decreased blood flow to the kidneys, which can happen in the case of bleeding, severe diarrhea, or burns.

Other causes of acute kidney injury include severe infections; severe allergic reactions; poisoning with substances, like antifreeze; or ingesting certain medications that can damage the kidneys, such as large quantities of nonsteroidal anti-inflammatories, like Ibuprofen.

Chronic kidney failure, or chronic kidney disease, happens when there’s a progressive decrease in kidney function, meaning that the number of functioning nephrons are gradually lost.

Common causes of chronic kidney disease are diabetes mellitus and hypertension. Both these conditions damage the blood vessels in the glomerulus.

Other causes include chronic infections, such as chronic pyelonephritis; infection of the kidneys; or blockage in the urinary system, like when there’s a large kidney stone or tumor.

One of the signs of renal failure is dehydration, which happens due to excessive loss of fluid. This usually happens pretty early in acute kidney injuries because the kidneys aren’t able to reabsorb water back into the bloodstream.

Another sign is swelling, caused by the build-up of fluid in the tissues of the body. This usually happens later in chronic kidney disease, when the kidneys aren’t able to excrete the excess fluid.

Another sign is hypertension, which happens mostly due to fluid overload in the bloodstream. Finally, there’s oliguria or anuria.

Oliguria is when an individual urinates less than 400 milliliters in 24 hours, and anuria is when someone urinates less than 100 milliliters, or no urine in 24 hours.

Now, keep in mind that renal failure, especially chronic kidney disease, can affect every body system, so other signs and symptoms can include nausea, vomiting, loss of appetite, fatigue, weakness, sleep problems, decreased mental alertness, muscle cramps, itchy skin, chest pain, and shortness of breath.

Individuals suffering from kidney failure often need dialysis to survive. Dialysis is the process through which waste products and fluids are removed from the body.

Basically, dialysis takes over the kidney’s job. An individual with acute kidney injury may temporarily need dialysis until their kidneys recover from the injury and start functioning normally.

However, an individual with severe chronic kidney disease must remain on dialysis for a long period of time or until they can have a kidney transplant.

There are two types of dialysis: hemodialysis and peritoneal dialysis. In hemodialysis, there’s a machine that contains filters and solutions that are able to clean the blood of waste products and remove excess fluid.

The machine used in hemodialysis is sometimes called an artificial kidney. In order for it to work, the individual’s blood is drawn intravenously, passed through the machine, and then returned to the person’s body through another vessel.

To make this process easier, an individual receiving long-term hemodialysis usually needs surgery to create a fistula to connect an artery directly to a nearby vein.

Another option is a surgical graft, where a tube is used to connect the two vessels. Either way, blood will flow from the artery into the vein, causing it to expand and bulge and making it easier to access.

The increased blood flow will also make the dialysis process quicker. In peritoneal dialysis, the peritoneal membrane, a membrane that lines the peritoneal cavity, is used as a filter to remove excess fluid and waste products.

In order to do so, a solution that can absorb waste products is placed into a person’s abdomen through a tube that’s been surgically inserted.

In order for the solution to work and absorb waste products, it has to remain in the abdominal cavity for a specific period of time. Afterwards, this solution is drained into a collecting bag and then discarded.

In order to keep waste products and excess fluid away, both types of dialysis must be performed several times a week for a certain period of time.