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Renal Failure

Renal Failure - What Does It Mean?

Renal failure (kidney failure) is the inability of the kidneys to perform their normal functions or when the kidneys are not able to function optimally.  The word renal has a Latin origin and means kidney-related.  The term failure, in the context of the kidneys, means "not functioning optimally or fully".

To get a clearer understanding of renal failure, it might be helpful to distinguish between kidney failure and kidney disease.  Although these two terms are sometimes used interchangeably, they have slightly different emphasis.

Kidney disease is any unhealthy condition or specific illness that affects the kidneys and impairs kidney function.  Kidney diseases can range from mild infections to life-threatening conditions such as kidney cancer.

As a result of kidney diseases, the normal functions of the kidneys may be affected, leading to kidney failure.  In other words, kidney disease is any illness that causes renal failure (i.e. decline in kidney function).

Another closely related term is renal insufficiency.  Renal insufficiency refers to a state in which the kidneys are not able to maintain homeostasis (ho-me-oh-stay-sis).  This primarily occurs when there is extensive damage to the nephrons within the kidneys.  (Nephrons are microscopic tube-like structures in the kidneys that are responsible for filtering the blood.)

Homeostasis is the ability of the body to maintain internal stability, even when the environment around it changes.  In a state of homeostasis, the body is able to detect harmful changes in its environment and activate mechanisms to counteract them.

It is possible to evaluate how well the kidneys are functioning by performing a series of tests, collectively referred to as kidney function tests.  These tests involve detailed analysis of the blood and urine, to assess kidney function.  They may also include the use of ultrasounds, magnetic resonance imaging (MRI), computed tomography (CT) scan, X rays, renal biopsy, and arteriogram (the recording of an arterial pulse) of the kidneys.  These tests help to determine the cause of renal failure and the level of remaining kidney function.

Sudden and rapid decline in kidney function is described as acute.  When kidney function declines over an extended period of time (3 months or more), it is referred to as chronic.

Chronic Kidney disease can range from mild to severe and is classified into different stages, from stage one (1) to stage five (5).  Stage 1 is the least severe and stage 5 the most severe. In stage 1, kidney function is minimally reduced and is usually classified as normal.   Kidney function progressively declines from stages 1 to 5, with stage 5 being the most severe stage. At stage 5, the kidneys do not function at all or function less than 10% of their optimal capacity.  This is described as end stage renal disease (ESRD).  Needless to say, without proper diagnosis and treatment, this will likely be fatal.

These classification stages are primarily determined by the Glomerular Filtration Rate (GFR).

GFR is the amount of filtrate formed per minute by the kidneys.  Filtrate (Glomerular filtrate) is the fluid extracted from the blood by the kidneys' Glomeruli, which is eventually converted to urine.


Acute kidney failure occurs when illness or injury temporarily damages the kidneys.  Consequently, the kidneys cannot adequately remove fluids and wastes from the body or properly regulate certain chemicals in the bloodstream.  Although this can cause some problems in the short term, with proper and timely treatment it can typically be reversed.  Often there is no permanent damage to the kidneys.

Acute kidney failure can be caused by many different illnesses, but appears most frequently as a complication of serious illnesses such as heart failure, liver failure, dehydration, severe burns, and hemorrhage (excessive bleeding).  Adopting a proactive approach to heath can greatly reduces the risk of many of these serious illnesses that contribute to renal insufficiency.  Acute renal failure may also be caused by an obstruction to the urinary tract or as a direct result of kidney disease, injuries, or an adverse reaction to a medicine.  These kidney conditions fall into three main categories: pre-renal, post-renal, and intra-renal conditions.

Pre-renal conditions do not damage the kidneys, but can cause diminished kidney function.  They are the most common causes of acute renal failure, and include: dehydration, hemorrhage, septicemia or sepsis (blood poisoning), heart failure, liver failure, and burns.

Post-renal conditions cause obstruction of the urinary tract.  These include inflammation of the prostate gland (prostatitis), enlargement of the prostate gland (benign prostatic hypertrophy), bladder or pelvic tumors, and kidney stone (calculi).

Intra-renal conditions involve direct injury to the kidneys or kidney disease. These include kidney infection, drug abuse, and acute inflammation of the kidneys' glomeruli.


Unlike acute renal failure, which is temporary, chronic kidney failure is long term and, in most cases, is irreversible.  This is extremely serious and can eventually lead to a total shut down of the kidneys (end stage renal disease).  Without proper treatment, to remove the wastes and excess fluids from the bloodstream, this condition can be fatal.

It is important to understand the effects of renal insufficiency on the body and general health.  The kidneys are the major organs in the body's natural filtration system.  They remove waste products such as urea and toxins, along with excess fluids from the bloodstream, in the form of urine.

When the kidneys fail (stop functioning as they should), then fluids and toxins begin to accumulate in the bloodstream.  As the fluids begin to build up, the patient may become puffy and swollen in the face (edematous), and they may experience fatigue and nausea.

Most symptoms of chronic kidney failure are not apparent until kidney disease is in an advanced stage.  The most common causes of chronic renal failure include diabetes mellitus, chronic inflammation of the kidneys' glomeruli (glomerulonephritis), hypertension (high blood pressure) and obesity.

It is extremely important for anyone who begins to experience symptoms of kidney failure to immediately seek professional medical assistance.  Some of these symptoms include hypertension, foamy or bloody urine, lower back pain and increased fatigue.  Early detection and treatment of renal failure can go a long way in minimizing its long term impact.

Many kidney disorders can be prevented, if timely proactive action is taken.  Proper diet and nutrition and some simple healthy lifestyle choices (such as regular exercise) can go a long way in preventing renal failure and minimizing its harmful effects.

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