Kidney Glossary

Acute Renal Failure

Kidney failure that happens quickly—within days or a week. It is often caused by injury or drug interactions. Acute renal failure usually can be reversed.

Adequacy

Enough dialysis to avoid symptoms of uremia. 

Anemia

A shortage of red blood cells that carry oxygen to the body's tissues. Symptoms include paleness, shortness of breath, weakness, irregular heartbeat, fuzzy thinking, fatigue, and sexual problems.

Arterial Line

Tubing connected to a needle inserted into the hemodialysis patient's vascular access. During dialysis, the arterial line carries blood away from the body and into the dialyzer (artificial kidney) on the dialysis machine.

Arteriovenous (AV) Fistula

A blood vessel that is made by surgically sewing together an artery and a vein (often in the forearm) to create the rapid blood flow from the heart needed for efficient hemodialysis. It is also commonly called a native fistula or fistula.

Arteriovenous Graft

An access that is made by connecting one end of a piece of artificial vein to the patient's vein and the other end to the patient's artery. The graft is a larger vessel with the rapid blood flow needed for efficient hemodialysis. It is commonly called a graft.

Bilateral Nephrectomy

Removal of both kidneys.

BUN

Blood Urea Nitrogen. A waste product, or toxin, that appears in the blood as protein from food is digested. BUN levels are a measure of how well dialysis is removing wastes from the blood. Normal ranges of BUN in healthy people are 5-18 mg/dL in children, 7-18 mg/dL in adults, and 8-20 mg/dL in adults over 60 years old. Higher levels are present in patients with kidney failure.

CAPD

Continuous Ambulatory Peritoneal Dialysis. Patients using this form of dialysis put dialysate fluid into the abdomen through a surgically placed catheter, or tube. This fluid comes in contact with the peritoneal membrane, a thin layer of tissue around the abdominal organs. Some of the toxins in the blood pass from blood vessels in the wall of the peritoneal membrane into the dialysate. The fluid, which may change from clear to slightly yellow, is then drained out of the body through the catheter. The process is usually repeated four or five times per day.

Catheter

A tube. In peritoneal dialysis, a small catheter is permanently inserted into the abdomen to allow dialysate fluid to enter and exit. Sometimes a central venous catheter is inserted into the subclavian or internal jugular vein just below the collar bone or in the neck or groin to allow temporary blood access for hemodialysis.

CCPD

Continuous Cycling Peritoneal Dialysis. Like CAPD, dialysate fluid is drained into the abdomen through a catheter. Instead of changing the fluid several times each day as in CAPD, a machine changes the fluid several times each night while the patient sleeps.

Chronic Renal Failure

Kidney failure that takes place over a long period of time. Chronic renal failure is usually not reversible.

Creatinine

Creatinine is produced normally by muscles and is used to measure kidney function. It is always higher than normal in dialysis patients. Normal ranges of creatinine are 0.3-0.7 mg/dL in children birth to three, 0.5-1.0 mg/dL in children 3-18 years old, and 0.6-1.3 mg/dL in adults.

Dialysate Fluid

A fluid used for dialysis that consists of a mixture of water, glucose, and certain elements (electrolytes) the body needs. Dialysate usually contains sodium, magnesium, chloride, potassium, and calcium. During dialysis, waste products in the blood pass through a porous (filtering) membrane or dialyzer into the dialysate fluid.

Dialysis

The movement of very small, microscopic particles (toxins) from one side of a porous (filtering) membrane to another. Waste products and excess chemicals (electrolytes) in the blood pass through the membrane into a solution that does not contain those toxins. Both peritoneal dialysis and hemodialysis pass blood through a membrane to filter out waste products and fluid into dialysate.

Dialyzer

A plastic artificial kidney that contains thousands of very thin, hollow, tube-like membrane fibers. Blood flows through the inside of the hollow membranes. The fibers are surrounded by dialysate. Toxins from the blood move through the membranes and into the dialysate. The blood remains inside the hollow tubes and is returned to the body, once cleaned.

Disequilibrium

Headaches and dizziness during dialysis. Disequilibrium can occur if dialysis removes a lot of fluid very quickly, or if blood pressure drops.

Dry Weight

A patient's weight without excess fluid. A patient can lose several pounds of fluid weight during a dialysis session. The actual amount depends upon the amount of fluid consumed between dialysis treatments.

Dwell Time

The length of time peritoneal dialysis patients keep fresh dialysate in the abdomen. After the dwell time is over, used dialysate is replaced with fresh dialysate either by the patient (using CAPD) or by a cycler machine (CCPD).

Edema

Swelling in soft tissues, especially in face, hands, feet, and ankles. May be caused by drinking too much liquid between dialysis treatments or inadequate dialysis.

EPOGEN® (EPO)

(Epoetin alpha) A DNA-engineered form of the human hormone erythropoietin used to treat anemia. EPO sends a message to the bone marrow to make more red blood cells, so patients have more energy and endurance. A hormone produced by healthy kidneys that signals the bone marrow to make red blood cells.

End-Stage Renal Disease

End-stage renal disease, or permanent kidney failure. ESRD occurs when kidney function is approximately 10% to 15% of normal or less, and the patient needs dialysis or a kidney transplant to live.

Exchange

The process of draining used peritoneal dialysate from the abdomen and putting in fresh dialysate. An exchange may be done by the patient or by a cycling machine.

Fistula

See Arteriovenous (AV) fistula.

The "5 Es"

The core principles of successful rehabilitation: Encouragement, Education, Exercise, Employment, and Evaluation.

Graft

See Arteriovenous graft.

Hematocrit (Hct)

The percentage of red blood cells in whole blood. Normal hematocrit is from 37% to 47% for women and from 42% to 52% for men. The NKF-DOQI recommended target hematocrit range for dialysis patients is 33% to 36% and most patients need regular doses of EPO and iron to stay at this level. Without enough red blood cells to carry oxygen to the tissues, patients feel tired and listless.

Hemodialysis

A type of dialysis in which the patient's blood is removed from the body and cleansed by a dialyzer, i.e., an artificial kidney. The patient's blood travels through needles placed into a specially created blood vessel. Blood is passed through the dialyzer, cleansed, and then returned to the body.

Hypertension

High blood pressure. This can be caused by too much salt intake, fluid build-up, or too much of the hormone renin, produced by the kidneys. Hypertension can cause headache, blurred vision, blindness, heart damage, and stroke.

Hypotension

Low blood pressure. This can occur if large amounts of fluid are removed from the blood vessels too quickly during dialysis. Hypotension can cause a fast pulse, dizziness, and sometimes nausea, vomiting, or fainting.

Kidney Failure

Loss of the ability of the kidneys to remove fluid and toxins from the body. The two most common causes of kidney failure are diabetes and high blood pressure. It may also be caused by other viral or hereditary disorders. Kidney failure is less often caused by damage related to medications, or by other conditions such as kidney stones or injuries.

Kt/V

This is a formula for prescribing adequate dialysis and checking to see if the patient is receiving enough dialysis. Kt/V is calculated by multiplying toxins removed, called clearance (K), by the amount of time (t) of the dialysis treatment, and dividing by the volume (V) of water in the body. The doctor uses blood tests to learn if the patient is getting enough dialysis. The recommended prescribed Kt/V for hemodialysis is 1.3, with a minimum actual Kt/V of 1.2. The recommended prescribed Kt/V for peritoneal dialysis is a minimum weekly Kt/V of 2.0. These figures are the floor, or minimum, only. A formula for calculating Kt/V for hemodialysis can be found in the AAKP Advisory: Inadequate Hemodialysis Increases the Risk of Premature Death, listed in the Resources section at the back of this booklet.

LORAC

The Life Options Rehabilitation Advisory Council. This group is made up of health care professionals, patients, business leaders, and researchers dedicated to helping dialysis patients realize their fullest potential.

Modality

A type or mode of treatment. In ESRD, the modalities of treatment include hemodialysis, peritoneal dialysis, and transplant.

Nephrology

The study of the kidneys. It is the medical specialty that deals with the diagnosis and treatment of kidney disease.

Nephrologist

A physician who specializes in studying the kidneys and helping patients with kidney problems.

Neuropathy

Nerve damage. It can be caused by diabetes. It can also be caused by uremia, or a build-up of toxins in the body. Too little dialysis over time can lead to nerve damage. Neuropathy can cause weakness, burning, tingling, and numbness, especially in the feet and lower legs, but also in the hands.

Peritoneal Dialysis

A form of dialysis that uses the body's own peritoneal cavity to hold dialysate fluid. The peritoneal membrane acts like a filter to allow toxins, excess chemicals, and fluid to move into dialysate. Peritoneal dialysis "exchanges" fresh dialysate for used dialysate, often several times a day. Exchanges can be done by the patient (see CAPD) or by a machine (see CCPD), or in some cases both types of exchanges are combined to help the patient get enough dialysis. Combination therapy may be called "PD Plus."

Peritoneal Membrane

The porous, double-layered, sac-like lining that surrounds the abdominal organs in the body's peritoneal cavity.

Peritoneum

The area surrounded by the peritoneal membrane, which includes the abdominal organs.

Rehabilitation

A return to stable health, a positive outlook, and enjoyable activities that make people feel better physically and mentally. A successful rehabilitation program uses medical treatment, counseling, education, diet, and exercise.

Renal

Related to the kidneys.

Toxins

Chemical waste products produced by metabolic processes in the body like digesting food, breathing, and mental and physical activity.

Uremia

A condition of excess toxins or impurities in the blood. Symptoms include weakness, lack of energy, poor appetite, weight loss, metallic or ammonia taste in the mouth, skin color changes, and worsening memory.

URR

Urea Reduction Ratio. Like Kt/V, URR is a way to measure dialysis adequacy. It is based on a ratio of the predialysis BUN level to the postdialysis BUN level. (See BUN). Patients can calculate their URR themselves using a formula contained in the AAKP Advisory: Inadequate Hemodialysis Increases the Risk of Premature Death, listed in the Resources section at the back of this booklet. The URR value should be 65% or higher.

Venous Line

In hemodialysis, the tubing that returns the clean blood from the dialyzer back to the patient through the access.