by Dr. Brooke Azie-Rentz
This month we are focusing on the Kidney; 2 small bean shaped organs located next to your spine on either side. I know what you are thinking: those 2 little organs, you can give one to another person and still go on living, how important could they be? After recently being on vacation and taxing my kidneys with dehydration from flying, running heaters in the blizzards of New England and the sweating from the hot sun of Jamaica, I can tell you I have seen their importance.
Honestly, when it comes to the kidneys, you have to take a page out of the lesson plan from one of my favorite teachers, Model. That is to step back and look at the “big picture.” To think that your kidneys are only responsible for making urine is just the tip of the iceberg! They are responsible for:
- Removing excess weight and fluid – the kidney filters 200 quarts of blood each day which yields 1-2 quarts of urine! The kidneys help maintain electrolyte balance by filtering electrolytes and water from blood, returning some to the blood, and excreting any excess minerals into the urine. Sodium always follows water, that is why it is important to take extra electrolytes when exercising or sweating due to the loss of sodium and chloride (NaCl – salt) when you sweat. Also, using electrolytes (salt) can help your body hold on to water versus just excreting it out through your kidneys. This is also why too much salt can lead to high blood pressure.
- Controlling blood pressure – when your blood volume gets too high or too low the kidney is able to produce hormones/enzymes to tell the body to vasoconstrict blood vessels. One of these hormones, known as renin, through a long complicated enzymatic process, tells the kidneys to absorb more sodium, and therefore more water, decreasing urine output and thereby increasing blood pressure.
- Making red blood cells – yet another hormone the kidneys are able of controlling, erythropoietin (EPO), is made by the kidney to tell the body to make Red blood cells (RBCs). When the kidneys are compromised, they make less of this hormone which in turn doesn’t stimulate the bone marrow to make RBCs, which means you end up anemic and depriving your cells of oxygen.
- Keeping bones healthy – Vitamin D, which is absorbed by your eyes/skin and ingested, is converted to the active form of Vitamin D by your kidneys and is responsible for regulating the absorption of calcium and phosphorus. This happens because when the calcium is not converted to the active form in the kidneys, the blood levels of calcium fall which activates the parathyroid hormone to reabsorb calcium from the bones, which leads to osteopenia/osteoporosis.
A second factor is that when the kidney is damaged, it cannot excrete phosphorus in your blood; these high levels of phosphorus also activate the parathyroid gland to tell the kidney to secrete more phosphorus. However, the parathyroid gland cannot choose to do one without the other, so as it tells the kidney to secrete more phosphorus, it also leeches calcium from the bones.
- Controlling pH – the measure of acid/base balance in your body is controlled by the kidneys either absorbing more bicarbonate from urine (to make blood more alkaline) or decreasing the excretion of hydrogen ions into the urine (to make the blood more acidic).
In the end, the kidney is a very complicated organ of great importance. The various hormones and enzymes work synergistically with the heart, liver, eyes, lungs, brain and other organs to help regulate many different aspects of our body. So the “big picture” here is that these little organs are critical to life! So take care of them. The best way to do this is to stay hydrated, get regular exercise, don’t smoke, drink moderately, eat healthy (watch salt intake) and monitor your blood sugar and blood pressure on a yearly basis.
Some random Kidney-Related questions:
Why do my feet and ankles swell after flying?
This actually occurs due to sitting for long periods of time in a cramped position, which in turn puts pressure on veins and lymphatic systems which can lead to a back flow of fluids and cause swelling. Combine this with the dehydration caused by the pressurized air system, which can cause your blood to be thicker and harder to move through your body, and your kidneys end up working extra hard. A good way to stop this is to drink extra fluids the day before leaving on your trip and to make sure to stand up and walk around as much as possible on the plane. Calf pumps in your seat and self massage are also helpful.
Why do I have to pee more when I drink alcohol or caffeine?
If you are anything like me, after even a cup of green tea I have to find the bathroom every 45 minutes, or for some people they call it “breaking the seal.” Turns out, caffeine is a diuretic (it makes you have to pee more than the amount of liquid you have consumed). However, the effects of caffeine are mitigated when it is drunk on a regular basis. So, when I do decide to have a cup of blue mountain coffee, I need to know where the bathroom is because I only drink about 1 cup per week when not on vacation. Alcohol is also a diuretic, but it also suppresses the release of Anti-diuretic Hormone (ADH), the hormone that makes you not have to pee. So, it is a double whammy! It makes you pee more, and without ADH, more water runs into your bladder making more watered down urine and more trips to the bathroom. That is why your urine is clearer the more alcohol you drink!
Can my eyes really turn yellow if I hold my pee too long?
No. But due to the detoxifying actions of the kidney, a functioning kidney is responsible for cleaning out toxins and maintaining pH balance. Therefore, holding your urine can lead to a buildup of toxins in your bladder that can reflux into your kidneys and ultimately get into your blood stream if not treated. This can cause toxicity and bad infections that can move throughout your body.