Renal Failure

Renal failure, also known as kidney failure or renal insufficiency, is a medical condition in which the kidneys fail to adequately filter waste products from the blood. The two main forms are acute kidney injury, which is often reversible with adequate treatment, and chronic kidney disease, which is often not reversible. In both cases, there is usually an underlying cause.

Kidney failure is mainly determined by a decrease in glomerular filtration rate, which is the rate at which blood is filtered in the glomeruli of the kidney. The condition is detected by a decrease in or absence of urine production or determination of waste products (creatinine or urea) in the blood. Depending on the cause, hematuria (blood loss in the urine) and proteinuria (protein loss in the urine) may be noted.

In kidney failure, there may be problems with increased fluid in the body (leading to swelling), increased acid levels, raised levels of potassium, decreased levels of calcium, increased levels of phosphate, and in later stages anemia. Bone health may also be affected. Long-term kidney problems are associated with an increased risk of cardiovascular disease.

Kidney failure can be divided into two categories: acute kidney injury or chronic kidney disease. The type of renal failure is differentiated by the trend in the serum creatinine; other factors that may help differentiate acute kidney injury from chronic kidney disease include anemia and the kidney size on sonography as chronic kidney disease generally leads to anemia and small kidney size.

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a rapidly progressive loss of renal function, generally characterized by oliguria (decreased urine production, quantified as less than 400 mL per day in adults, less than 0.5 mL/kg/h in children or less than 1 mL/kg/h in infants); and fluid and electrolyte imbalance. AKI can result from a variety of causes, generally classified as prerenal, intrinsic, and postrenal. The underlying cause must be identified and treated to arrest the progress, and dialysis may be necessary to bridge the time gap required for treating these fundamental causes.

Chronic kidney disease (CKD) can also develop slowly and, initially, show few symptoms. CKD can be the long term consequence of irreversible acute disease or part of a disease progression.

Acute kidney injuries can be present on top of chronic kidney disease, a condition called acute-on-chronic kidney failure (AoCRF). The acute part of AoCRF may be reversible, and the goal of treatment, as with AKI, is to return the patient to baseline kidney function, typically measured by serum creatinine. Like AKI, AoCRF can be difficult to distinguish from chronic kidney disease if the patient has not been monitored by a physician and no baseline (i.e., past) blood work is available for comparison.

Symptoms can vary from person to person. Someone in early stage kidney disease may not feel sick or notice symptoms as they occur. When kidneys fail to filter properly, waste accumulates in the blood and the body, a condition called azotemia. Very low levels of azotaemia may produce few, if any, symptoms. If the disease progresses, symptoms become noticeable (if the failure is of sufficient degree to cause symptoms). Kidney failure accompanied by noticeable symptoms is termed uraemia.


Symptoms of kidney failure include the following:

High levels of urea in the blood, which can result in:

Vomiting and/or diarrhea, which may lead to dehydration

Nausea

Weight loss

Nocturnal urination

More frequent urination, or in greater amounts than usual, with pale urine

Less frequent urination, or in smaller amounts than usual, with dark coloured urine

Blood in the urine

Pressure, or difficulty urinating

Unusual amounts of urination, usually in large quantities

A buildup of phosphates in the blood that diseased kidneys cannot filter out may cause:

Itching

Bone damage

Nonunion in broken bones

Muscle cramps (caused by low levels of calcium which can be associated with hyperphosphatemia)

A buildup of potassium in the blood that diseased kidneys cannot filter out (called hyperkalemia) may cause:

Abnormal heart rhythms

Muscle paralysis

Failure of kidneys to remove excess fluid may cause:

Swelling of the legs, ankles, feet, face and/or hands

Shortness of breath due to extra fluid on the lungs (may also be caused by anemia)

Polycystic kidney disease, which causes large, fluid-filled cysts on the kidneys and sometimes the liver, can cause:

Pain in the back or side

Healthy kidneys produce the hormone erythropoietin that stimulates the bone marrow to make oxygen-carrying red blood cells. As the kidneys fail, they produce less erythropoietin, resulting in decreased production of red blood cells to replace the natural breakdown of old red blood cells. As a result, the blood carries less hemoglobin, a condition known as anemia. This can result in:

Feeling tired and/or weak

Memory problems

Difficulty concentrating

Dizziness

Low blood pressure

Normally, proteins are too large to pass through the kidneys, however, they are able to pass through when the glomeruli are damaged. This does not cause symptoms until extensive kidney damage has occurred, after which symptoms include:

Foamy or bubbly urine

Swelling in the hands, feet, abdomen, or face

Other symptoms include:

Appetite loss, a bad taste in the mouth

Difficulty sleeping

Darkening of the skin

Excess protein in the blood

With high dose penicillin, people with kidney failure may experience seizures