What Does the Kidney Do?

Posted by: DaVita Clinical Research

Anyone travelling on a long highway after 3 cups of coffee becomes really aware of their kidneys very quickly.

But, besides getting rid of excess water, the kidney has other functions essential to life. In fact, if it weren’t for the kidneys’ ability to regulate the internal chemistry of our bodies, we would still be worms flopping around in the primordial sea.

What does the kidney do anyway? The seven functions of the kidney:

1.) Regulation of Water and Electrolyte Balance: Water is essential to life. But too much and the lungs get flooded with fluid.  Too little and blood pressure drops. Electrolytes, which are basically the salts in the blood, must be kept at very specific levels or else cells cannot function.

2) Excretion of Metabolic Waste: We need food to survive, but after the body has used the energy and building blocks from what we take in, wastes result. The kidney works like a filter and a processing plant to get rid of waste such as urea and some hormones

3.) Excretion of Substances that Affect Body Function: This refers to certain hormones, but in day-to-day life, this often means the elimination of drugs. Penicillin is good, for instance, but once it’s done its job the kidney filters it out.

4.) Regulation of Blood Pressure: Those salts we talked about earlier, mainly sodium, help with keeping the amount of fluid in the blood stream and tissues constant. The kidneys also receive signals from the brain which tell them to release hormones to make the blood vessels the right diameter to keep blood pressure stable.

5.) Regulation of Red Blood Cell Production: Being attached to the aorta, the kidney is in a good spot to detect oxygen levels in the blood. Specialized cells in the kidneys can detect low oxygen levels and make a hormone called erythropoietin. This hormone tells the bone marrow to make more red blood cells which carry oxygen to all of the body’s tissues, like the brain and heart.

6.) Regulation of Vitamin D Production: The calcium and phosphorus in milk have to be kept at just the right amount, too much or too little can cause problems with nerves, the heart, and even the bones. The kidney makes the Vitamin D you consume into a super potent form which is involved with calcium and phosphorus management.

7.) Gluconeogenesis: A big long word for “making glucose”. Do we have to get up at night to eat? Of course not. The kidneys help the liver make glucose overnight to keep our bodies working the way it ought to.

There you have it. I hope this gives you a new appreciation for how essential the kidneys are to keeping you healthy!

-Dr. Jeffrey Connaire, Medical Director of Nephrology Services