The body takes nutrients from food and converts them to energy. After the body has used all the food components that it needs, waste products are left behind in the bowel and in the blood.
The kidneys and urinary system help to excrete the waste products and also keep chemicals, such as potassium and sodium, and water in balance. Kidneys filter and remove several toxic materials from the body that are the products of food metabolism. These waste materials can cause several problems to the body if they build up. The kidneys also control the fluid and acid-base balance in the body
Two kidneys, a pair of purplish-brown organs, are located below the ribs toward the middle of the back. Their function is to:
Remove liquid waste from the blood in the form of urine
Keep a stable balance of salts and other substances in the blood
The kidneys remove urea from the blood through tiny filtering units called nephrons. There are about one million nephrons in each kidney, located in the medulla and the cortex. Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
Once the urine is formed, it passes through the nephrons and down the renal tubules of the kidney. Urine collects in the calyces and renal pelvis and moves into the ureter. From here it flows down into the bladder.
In addition to filtering waste from the blood and assisting in the balance of fluids and other substances in the body, the kidneys perform other vital functions. The kidneys:
Release hormones, such as renin, that help to regulate blood pressure
Produce erythropoietin. This is a hormone that aids formation of red blood cells.
Convert vitamin D into a form that can be used by the body's tissues
Interact with corticosteroids (made by the adrenal glands that sit on top of the kidney) that help to regulate kidney function and the body’s inflammatory response system
Nephrology is the branch of medicine concerned with the diagnosis and treatment of conditions related to the kidneys. Healthcare providers who specialize in kidney disease are called nephrologists. Other health professionals who treat kidney problems include primary care providers, pediatricians, transplant specialists, and urologists.
Problems with the kidneys may include conditions, such as kidney failure, kidney stones, and kidney cancer. These problems with the kidneys may be caused by the following:
Aging. As we age, changes in the structure of the kidneys can cause them to lose some ability to remove wastes from the blood, and the muscles in the ureters, bladder, and urethra tend to lose some of their strength. However, this alone does not cause chronic kidney diseases.
Illness or injury. Damage to the kidneys caused by illness or an injury can also prevent them from filtering the blood completely or block the passage of urine.
Toxicity. The kidneys may be damaged by substances, such as certain medicines, a buildup of some substances in the body, or toxic substances such as poisons.
Diseases of the kidney and urinary tract remain a major cause of illness and death in the United States. The National Kidney Foundation states that more than 26 million Americans are affected by kidney and urologic diseases, and millions more are at risk.
The following are the most common symptoms of kidney disease. However, each individual may experience symptoms differently. Symptoms may include:
Itchiness all over the body
Blood in the urine
Loss of appetite
Nausea and/or vomiting
Puffiness around eyes and/or swelling of hands and feet
Skin may darken
Muscle cramps or pain in small of back just below the ribs (not aggravated by movement)
High blood pressure
The symptoms of a kidney disease may look like other conditions or medical problems. Always talk with your healthcare provider for a diagnosis.