Understanding Kidney Disease - Basic Information

What Is Kidney Disease?

The kidneys, two fist-sized organs located on either side of your spine just above the waist, perform several life-sustaining roles. They cleanse your blood by removing waste and excess fluids, maintain the balance of salt and minerals in your blood, and help regulate blood pressure.

When the kidneys become damaged, waste products and fluid can build up in the body, causing a swelling in your hands and feet, shortness of breath, problems with urination. If left untreated, diseased kidneys may eventually stop functioning completely. Loss of kidney function is a serious -- potentially fatal -- condition.

Each bean-shaped kidney is 4 to 5 inches long and contains about a million nephrons, which are like tiny pouches. Each nephron has a filter at one end, called a glomerulus, to filter your blood. Your overall kidney function can be measured by how quickly blood is filtered through these glomeruli. This measurement is called the glomerular filtration rate.

Healthy kidneys handle several specific roles:

• Maintain your body's balance of water and concentration of minerals such as sodium, potassium, magnesium, and phosphorus in your blood.
• Remove waste by-products from the blood after digestion, muscle activity, and exposure to chemicals or medications.
• Produce renin, an enzyme that helps regulate blood pressure.
• Produce erythropoietin, which stimulates red blood cell production.
• Produce an active form of vitamin D, needed for bone health.

What Causes Acute Kidney Failure?

The loss of kidney function over several hours or days is called acute kidney failure, also known as acute renal failure (ARF). Kidney failure can occur following a traumatic injury with blood loss, the sudden reduction of blood flow to the kidneys, damage to the kidneys from shock during a severe infection called sepsis, or damage from certain drugs or toxins.

Acute kidney failure can also happen during a pregnancy complication, such as eclampsia, pre-eclampsia, or related HELLP Syndrome.

Inhaling or swallowing certain toxins can also cause the kidneys to slow or stop functioning suddenly. These toxins include methyl (wood) alcohol, carbon tetrachloride, ethylene glycol in antifreeze, and poisonous mushrooms.

Marathon runners and other athletes who don't drink enough fluids while competing in long-distance endurance events may suffer acute kidney failure due to a sudden breakdown of muscle tissue. This muscle breakdown releases a chemical called myoglobin that can damage the kidneys.

Infection with streptococcal bacteria can also result in acute kidney failure. Certain medications or medical treatments may have unpredictable effects on the kidneys and can cause a sudden decrease in kidney function.

What Causes Chronic Kidney Disease?

Kidney damage and decreased function lasting longer than 3 months is called chronic kidney disease (CKD). Chronic kidney disease is particularly dangerous since you may not have any symptoms until considerable, often irreparable, kidney damage has been done.