Overview of the kidneys

When you find out you have been diagnosed with chronic kidney disease (CKD), it can be overwhelming. Sometimes you must suddenly change a lifetime of habits. One way to maintain as good a health as possible is to learn about your kidneys. This is an overview of the kidneys. 

Where are your kidneys?

Kidneys are bean-shaped organs located on either side of your spine at the lowest level of your rib cage. Kidneys may be small organs, but they work hard. Each kidney is about the size of a fist and weighs between four to six ounces. The kidneys rest above a person’s waist. The left kidney is slightly higher and a little larger than the right kidney, which is located next to the liver. Both kidneys are protected by the rib cage. 

What do kidneys do?

If your organs had professions, your kidneys would be chemists. Kidneys clean and balance your entire body’s blood supply. Approximately 200 quarts of blood are processed through your kidneys every 24 hours. 

The kidney’s primary function is cleaning the blood by removing waste products and excess fluid from the body through urine production. The kidneys also: 

• regulate blood pressure by producing the enzyme rennin
• control the body’s mineral and acidity levels
• keep bones strong and healthy by producing calcitriol, an active form of vitamin D
• stimulate the production of red blood cells by producing the hormone erythropoietin

How do kidneys work?

The body extracts nutrients from food and beverages, and uses them to keep the body functioning properly. What the body cannot use is left behind as waste products which are eliminated either through bowel movements or filtered out by the kidneys. Blood urea nitrogen, for example, is a waste product left over from protein metabolism. 

Inside the kidneys

With each heartbeat, blood flows through the kidneys. Each kidney contains up to a million filtering units called nephrons. Each nephron is made up of tiny capillary loops called a glomerulus. Millions of glomeruli (plural of glomerulus) filter urea, other waste and excess water from the blood.  

Each glomeruli attaches to the opening of a small fluid-collecting tube, called a tubule. The clean (filtered) blood returns to the blood stream, while the tubules sort out what the glomeruli filtered from the blood. The tubules save the needed substances and remove any waste. 

The tubules lead to the collecting duct where urine is drained into a funnel-shaped sac called the renal pelvis. Each kidney has a ureter (a muscular duct) that connects the renal pelvis to the bladder. Urine from the kidneys flows through the ureters into the bladder and is passed out of the body through the urethra. Approximately 2 quarts of urine is produced every 24 hours. 

Helping your kidneys

Becoming proactive can help sustain kidney function. Here are some helpful tips to maintain a healthy life and help your kidneys working:  

• Keep scheduled doctors appointments.
• Take prescribed medicine correctly.
• Consult your doctor before taking any over-the-counter medication or supplement.
• Maintain a healthy weight.
• Check your blood pressure and do what it takes to keep it in the normal range.
• If you have diabetes, manage your blood sugar to keep it as close to normal as possible.
• Exercise can lower high blood pressure, which helps your heart and kidneys.
• Consult a renal dietitian and follow a kidney-friendly diet if prescribed.
• Do not smoke.
• Limit or avoid drinking alcohol excessively.

Kidney failure

Kidney failure occurs when the kidneys can no longer work to do the normal functions mentioned above. These are the most common causes of kidney failure: 

• Diabetes
• High blood pressure
• Glomerular kidney diseases
• Polycystic kidney disease (and other genetic diseases)
• Kidney-related birth defects
• Autoimmune kidney diseases

Diabetes and high blood pressure are the leading causes of chronic kidney disease. Some of the conditions mentioned can also happen at any age. 

Summary

Kidneys are bean-shaped organs that work non-stop to maintain the chemical balance of your body by cleaning your blood, producing hormones and enzymes and managing fluid levels.

Related articles on DaVita.com

• Overview about kidneys
• What kidneys do and how they fail

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