Your Kidneys: Not Just A Waste Disposal Team

We are used to thinking of our kidneys as filters that rid our bodies of excess water, but that hardly does justice their full range of responsibilities. And the kidneys do indeed play a key role in maintaining the body’s fluid balance within a very narrow range; even a 1% increase in blood sodium, for example, will make a person thirsty enough to take a drink in order to return the fluid balance to normal. The waste filtration units inside the kidneys are called nephrons. Each kidney has about a million nephrons. Within the nephrons are dense forests of tiny capillaries called glomeruli, through which the entire blood supply cycles up to TK times a day [needs check].

But what is missing from the description is the dynamic, open dialogue the kidneys maintain with the blood, constantly monitoring and adjusting levels of key substances, depending on what the body needs. In a sense, the kidneys act as the brain and endocrine system for the blood supply. Specialized cells in the kidney that are very sensitive to low oxygen levels produce a hormone called erythropoietin (EPO), which in turn promotes the formation of red blood cells in the bone marrow. The boost in red blood cell production increases the oxygen-carrying capacity of the blood. LESS

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Proteins are essential for body growth, development, and health, but they are not normally found in the urine. Healthy kidneys filter and recycle blood serum proteins; if the kidneys are damaged, however, they become less effective at filtering, and detectible amounts of protein begin leak into the urine.

Protein in the urine may be a temporary elevation due to infection, medication, vigorous exercise or stress (in pregnant women, elevated urine protein levels can be associated with preeclampsia). But high levels of urine protein (proteinuria) are often seen in chronic diseases, such as diabetes and hypertension; the higher the levels, the greater the underlying damage. Proteinuria is also associated with bladder cancer, congestive heart failure, heavy metal poisoning, polycystic kidney disease, infections and drug therapies toxic to kidneys.

Urine protein tests detect and measure protein being excreted in the urine. Follow-up tests can determine which proteins are present, which can help determine the cause of the problem. Symptoms of kidney disease often don’t appear until 80-90% of function has already been lost (an estimated 23 million adults have evidence of chronic kidney disease). When kidneys fail, there are usually only 2 options: a kidney transplant or dialysis. In some cases of acute failure, kidney function may recover, but in most cases, damage is permanent. LESS

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A complete urinalysis is a group of chemical and microscopic tests that detect substances not normally found in the urine, such as protein, but also glucose, bilirubin, red or white blood cells, crystals, bacteria, yeast or mucus. These may be present because there are elevated concentrations in the blood and the body is trying to flush them out in the urine, or because disease or damage have made the kidneys less effective. In most cases, the higher the levels of these substances in the urine, the more likely there is an underlying problem, but results may not indicate exactly what is wrong, or whether it is a temporary or chronic condition. A urine screen consists of three distinct testing phases:

1. a visual examination that evaluates the urine's color, clarity, and concentration (cloudy urine is often an easy visual clue of infection);
2. a chemical analysis that tests for the presence and amount of various substances (usually a “dipstick” with multiple reactive strips that change color if certain substances are present or if their levels are above normal);
3. and a microscopic analysis that identifies and counts the type of cells, cell fragments, crystals, and other components, such as bacteria and mucus, that can be present in urine.

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