Chronic Kidney Disease (CKD)

Illustration of the kidneys, urinary tract, and bladder.

Illustration of kidney and surrounding anatomy.

Chronic kidney disease

Chronic kidney disease occurs when one suffers from gradual and usually permanent loss of kidney function over time. This happens gradually, usually over months to years. Chronic kidney disease is divided into five stages of increasing severity (see Table 1 below). The term "renal" refers to the kidney, so another name for kidney failure is "renal failure." Mild kidney disease is often called renal insufficiency.

With loss of kidney function, there is an accumulation of water, waste, and toxic substances in the body that are normally excreted by the kidney. Loss of kidney function also causes other problems such as anemia,high blood pressure, acidosis (excessive acidity of body fluids), disorders of cholesterol and fatty acids, and bone disease.

Stage 5 chronic kidney disease is also referred to as kidney failure, end-stage kidney disease, or end-stage renal disease, wherein there is total or near-total loss of kidney function. There is dangerous accumulation of water, waste, and toxic substances, and most individuals in this stage of kidney disease need dialysis or transplantation to stay alive.

Unlike chronic kidney disease, acute kidney failure develops rapidly, over days or weeks.

• Acute kidney failure usually develops in response to a disorder that directly affects the kidney, its blood supply, or urine flow from it.
• Acute kidney failure is often reversible, with complete recovery of kidney function.
• Some patients are left with residual damage and can have a progressive decline in kidney function in the future.
• Others may develop irreversible kidney failure after an acute injury and remain dialysis-dependent.

Table 1. Stages of Chronic Kidney Disease

Stage	Description	GFR* mL/min/1.73 m2
1	Slight kidney damage with normal or increased filtration	More than 90
2	Mild decrease in kidney function	60 to 89
3	Moderate decrease in kidney function	30 to 59
4	Severe decrease in kidney function	15 to 29
5	Kidney failure	Less than 15 (or dialysis)
*GFR is glomerular filtration rate, a measure of the kidney's function.

Chronic Kidney Disease Causes

Although chronic kidney disease sometimes results from primary diseases of the kidneys themselves, the major causes are diabetes and high blood pressure.

• Type 1 and type 2 diabetes mellitus cause a condition called diabetic nephropathy, which is the leading cause of kidney disease in the United States.
• High blood pressure (hypertension), if not controlled, can damage the kidneys over time.
• Glomerulonephritis is the inflammation and damage of the filtration system of the kidneys, which can cause kidney failure. Postinfectious conditions and lupus are among the many causes of glomerulonephritis.
• Polycystic kidney disease is a hereditary cause of chronic kidney disease wherein both kidneys have multiple cysts.
• Use of analgesics such as acetaminophen(Tylenol) and ibuprofen (Motrin, Advil) regularly over long durations of time can cause analgesic nephropathy, another cause of kidney disease. Certain other medications can also damage the kidneys.
• Clogging and hardening of the arteries (atherosclerosis) leading to the kidneys causes a condition called ischemic nephropathy, which is another cause of progressive kidney damage.
• Obstruction of the flow of urine by stones, an enlarged prostate, strictures (narrowings), or cancers may also cause kidney disease.
• Other causes of chronic kidney disease include HIV infection, sickle cell disease, heroin abuse, amyloidosis, kidney stones, chronic kidney infections, and certain cancers.

If one has any of the following conditions, they are at higher-than-normal risk of developing chronic kidney disease. One's kidney function may need to be monitored regularly.

• Diabetes mellitus type 1 or type 2
• High blood pressure
• High cholesterol
• Heart disease
• Liver disease
• Amyloidosis
• Sickle cell disease
• Systemic lupus erythematosus
• Vascular diseases such as arteritis, vasculitis, or fibromuscular dysplasia
• Vesicoureteral reflux (a urinary tract problem in which urine travels from the bladder the wrong way back toward the kidney)
• Require regular use of anti-inflammatory medications
• A family history of kidney disease

Chronic Kidney Disease Symptoms and When to Seek Medical Care

The kidneys are remarkable in their ability to compensate for problems in their function. That is why chronic kidney disease may progress without symptoms for a long time until only very minimal kidney function is left.

Because the kidneys perform so many functions for the body, kidney disease can affect the body in a large number of different ways. Symptoms vary greatly. Several different body systems may be affected. Notably, most patients have no decrease in urine output even with very advanced chronic kidney disease.

Effects and symptoms of chronic kidney disease include:

• need to urinate frequently, especially at night (nocturia);
• swelling of the legs and puffiness around the eyes (fluid retention);
• high blood pressure;
• fatigue and weakness (from anemia or accumulation of waste products in the body);
• loss of appetite, nausea and vomiting;
• itching, easy bruising, and pale skin (from anemia);
• shortness of breath from fluid accumulation in the lungs;
• headaches, numbness in the feet or hands (peripheral neuropathy), disturbed sleep, altered mental status (encephalopathy from the accumulation of waste products or uremic poisons), and restless legs syndrome;
• chest pain due to pericarditis (inflammation around the heart);
• bleeding (due to poor blood clotting);
• bone pain and fractures; and
• decreased sexual interest and erectile dysfunction.

When to Seek Medical Care

Several signs and symptoms may suggest complications of chronic kidney disease. One should call a health care professional if they notice any of the following symptoms:

• change in energy level or strength;
• increased water retention (puffiness or swelling) in the legs, around the eyes, or in other parts of the body;
• shortness of breath or change from normal breathing;
• nausea or vomiting;
• lightheadedness;
• bone or joint pain;
• easy bruising; or
• itching.

If a woman has known kidney problems, she should see a health care professional right away if she knows or suspects that she is pregnant.

See a health care practitioner as recommended for monitoring and treatment of chronic conditions such as diabetes, high blood pressure, and high cholesterol.

The following signs and symptoms represent the possibility of a severe complication of chronic kidney disease and warrant a visit to the nearest hospital emergency department.

• Change in level of consciousness -- extreme sleepiness or difficult to awaken
• Severe fatigue
• Chest pain
• Difficulty breathing
• Severe nausea and vomiting
• Severe bleeding (from any source)
• Muscle weakness