Diseases of the kidney are a major health concern in the United States, affecting more than 40 million Americans and causing more than 100,000 deaths annually. Impaired kidney function can occur suddenly or take place gradually over months and years. The condition can be temporary and reversible or permanent and life-threatening. In either case, without dialysis treatment or kidney transplant, the condition is life threatening.
In addition to physical trauma or damage from an accident, common conditions that lead to kidney failure include diabetes, uncontrolled hypertension (or high blood pressure) and an inflammation of the kidneys called glomerulonephritis. Other possible causes of kidney disease or failure can come from kidney stones, reduced blood flow to the kidneys, diseases such as systemic lupus erythematosus or certain drugs. Inherited kidney diseases, most commonly polycystic kidney disease, can also cause kidney failure.
Although a single kidney is generally capable of providing adequate function, when both kidneys fail the body suffers serious consequences. There is an accumulation of toxic substances (urea and creatinine) and an increase in the volume of water in the body. This excess water results in swelling of tissues and high blood pressure and prevents normal activity of other organs in the body such as the heart and lungs. In addition, normal acidity and chemical balance cannot be maintained without adequate kidney function. For example, if the body cannot rid itself of excess phosphate, calcium levels will drop resulting in bone disease.
If total kidney function drops below 10 percent of normal capacity and the impairment is irreversible and permanent, the condition is known as end-stage renal disease (ESRD).
Normally, the human body has two kidneys which are oval-shaped organs located at the back on the right and left side and partly covered by the lower ribs. In an average adult, these organs are approximately four to six inches in height and weigh a little over five ounces each. Each kidney is comprised of about one million units called nephrons, with each nephron consisting of a tube-like structure called a tubule. The closed end of the tubule forms a cup-shaped structure called a glomerular capsule, surrounding a network of tiny blood vessels called the glomerulus, which filters the blood. Filtrate drains into the tubule where its concentration is altered to form urine which flows through ureters to the bladder and is stored there until being eliminated from the body through the urethra.
Healthy kidneys produce a total of about 1.5 to 2.5 quarts of urine daily, which consists of waste products and excess water. Kidneys function to adjust the body's balance of various chemicals (sodium, potassium, calcium, phosphorus, dextrose and others) and monitor the blood's acidity, and produce certain hormones such as erythropoietin (EPO). The hormones help to regulate blood pressure, stimulate red blood cell production and promote strong bones.