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About the Kidneys

Most people have two functional kidneys. The kidneys produce urine that drains through narrow tubes (called ureters) into the bladder. The kidneys are usually located in each flank protected by muscles of the back and ribcage. The kidneys are contained within a fibrous sheath called the Gerota's fascia and surrounded by a layer of fat. The kidney capsule is a thin layer that covers the outer surface of the kidney (similar to the red peel of an apple). The primary vein that drains the kidney (renal vein) merges with the vein that takes blood to the heart (vena cava). An adrenal gland is located above each kidney within Gerota's fascia.

The adrenal glands, which are not part of the kidney, are located near the top of each kidney. The adrenal glands regulate blood sugar, potassium, body fluids and sex hormones. They also control the body's response to stress by producing a hormone called adrenaline.

The kidney performs many bodily functions, such as controlling fluid balance, regulating electrolytes (e.g., sodium, potassium, calcium, magnesium), preventing acid buildup, eliminating waste products, producing urine, and regulating blood pressure. The kidney also manufactures a hormone called erythropoietin that stimulates the production of red blood cells.

When the kidneys are damaged or a significant portion of kidney tissue is removed, the normal processes listed above may be impaired. In most cases, mild to moderate impairment causes very minor problems. In cases when kidney function is severely impaired, dialysis may be required.