As discussed in some of our previous articles, the kidneys are responsible for filtering the blood to make urine, eliminating waste products from the body. Where do these waste products come from?

Some are derived from food. An example is potassium, an electrolyte present in many fruits and other foods. Diets high in potassium are generally healthy for people without kidney disease and are recommended to lower the risk of developing high blood pressure. However, if potassium accumulates in the body, for example due to excessive intake in patients with kidney disease, it can be very dangerous.

Healthy kidneys are extremely efficient at removing excess potassium, usually keeping the concentration in the blood very steady.

Protein, another important constituent of a healthy diet, is broken down to various nitrogen-containing products that can also be dangerous if allowed to accumulate in the blood. Breakdown products of proteins come from our diet or from turnover of the cells from our own bodies.

These nitrogen-containing chemicals are thought to be some of the main culprits causing patients with chronic kidney disease to feel sick. The kidneys also remove many drugs and poisons from our blood.

When they work correctly, the kidneys are astoundingly efficient in removing all of these harmful substances. They filter about 40 gallons of blood every day to achieve this feat. Not bad for a couple of organs each only the size of your fist!

Unfortunately, kidney disease is all too common: About 1 in 9 adults in the United States have chronic kidney disease, decreasing the effectiveness of this toxin-removing system.

The most common causes of kidney disease are diabetes and hypertension.

What happens when kidney function starts to decline? Initially, there are typically no symptoms. A decrease in kidney function down to as low as 30 percent might allow a person to continue feeling quite well.

Many people therefore develop quite severe degrees of kidney disease without realizing it. So it’s worth having your kidney function checked if you have any risk factors for kidney disease. I recommend screening for kidney disease in any person with diabetes, high blood pressure, or a family history of kidney disease.

The screening typically involves a blood and urine test and measurement of blood pressure. Many other medical conditions raise the risk of kidney disease; your doctor can tell you if you should be screened.

More severe kidney disease can cause many symptoms including weakness, fatigue, nausea, wasting, shortness of breath and itching. In the final stages of kidney disease, dialysis or transplantation becomes necessary to preserve life.

Fortunately, if kidney disease is detected early, there are very effective treatments that can slow down the decline in kidney function. It can be difficult to keep taking medicine to prevent a disease that isn’t causing any symptoms at the time, but the long-term results of improved kidney function are well worth it.