"Many Important Functions"
Our kidneys perform many important functions. First, they remove excess fluid from our body. When we drink fluids, our kidneys determine how much fluid we need in our body to stay healthy, as well as how much needs to be eliminated. Excess fluid is eliminated in the urine.
The other vital function of the kidney is the elimination of salt. A high-salt diet can raise our BP and make us feel bloated from fluid retention. When we eat a salty meal, the kidney controls how much salt we need in our body and how much salt needs to be excreted in the urine. In kidney failure, our bodies cannot get rid of salt and our BP will increase even if we eat a low-salt diet.
Vitamin D and EPO
The kidney also produces two hormones that are important in keeping our bones strong and making sure we have enough red blood cells (RBCs) to circulate oxygen throughout our bodies. The kidney produces the active form of vitamin D. Vitamin D is generated in our skin by sun exposure. Vitamin D can also be absorbed from our intestinal tract from the foods we eat. Vitamin D requires activation before it helps us absorb the mineral (calcium) that keeps our bones strong. Activation of vitamin D occurs first in the liver and then in the kidneys. When our liver or kidneys fail, we cannot produce active vitamin D and our bones gradually start to break down.
The kidneys also make a hormone called erythropoietin (EPO). EPO tells the bone marrow to make more RBCs when our RBCs get old and die. Without EPO, we become anemic and may feel tired and complain of no energy.
How to Save Our Kidneys
People with kidney disease should be pro-active and develop a plan to save remaining kidney function so they can delay the onset and treatment of kidney failure. For example, if someone has 50% of their kidney function but does nothing to help their kidneys, they may lose an additional 10% of kidney function per year and may need dialysis in four years. However, if the same individual can develop a treatment plan that helps prevent kidney injury, they may lose only 5% of their kidney function per year and may not need dialysis for 8-10 years! If kidney function loss can be slowed down to 1% per year, the patient may never need dialysis.
The kidneys are vascular organs that receive blood from the heart. The blood vessels of the body can be compared to the plumbing system in our homes: As the pipes in your home get clogged with dirt, hair, and rust, the flow of water through the pipes gets disrupted. This may result in a decrease in water pressure or even a leak that requires re-piping. Diseases such as diabetes mellitus, high BP, high cholesterol, and injury from kidney toxins affect our body's plumbing system, causing blood vessels to get clogged and injured. Over time, if these diseases are not treated, the blood vessels going to our vital organs (brain, heart, and kidneys) become blocked, resulting in damage to the organ to which they are supplying blood.
To protect our kidney from damage and to prevent further loss of kidney function, we must:
Kidney Function
The definition of CKD is the occurrence of kidney damage for more than three months, or testing that shows that the kidney is working at less than 60% of normal. The percent kidney function is calculated form a blood test that measures creatinine. This is a protein released into the blood at a constant rate. The creatinine level in the blood is determined by the rate it is removed by the kidney. As kidney function decreases, serum creatinine levels increase.
Although kidney function is now determined by a computer program in most laboratories, a simple formula (what we used before we had fancy computer programs) can be used to help us understand the relationship between blood creatinine and kidney function.
There are many Internet sources available to help you determine your current level of kidney function. One of the best is found on the website: www.kdoqi.org. This website has useful information on kidney disease and guidelines for its treatment. On this site is a section called the GFR calculator. GFR stands for glomerular filtration rate and refers to the kidney's ability to filter and clean blood. (The kidney is made up of many small glomeruli.) The computer calculation of GFR can be determined based on your serum creatinine level, your race, and your gender.
Stages of Kidney Disease
Once your level of kidney function has been determined, you can then determine which stage of kidney disease you are in. Shown below are the various stages of kidney disease:
Stage Description Percent Function
One Minimal injury Greater than 90%
Two Mild injury 60%-89%
Three Moderate injury 30%-59%
Four Severe injury 15%-29%
Five Kidney failure Less than 15%
Take It Seriously
Kidney disease should be taken very seriously, and aggressive therapy should be offered to all patients with this life-threatening condition. Our goal is not just to prevent you from having to go on dialysis, but to save lives by helping prevent people from entering the later stages (stages four and five) of kidney disease. The best way to save your kidneys is to:
Reduce the pressure inside and outside the kidneys through necessary medications;
Lower your blood cholesterol and blood sugar if you have diabetes or high cholesterol levels; and
Avoid medications that can hurt the kidneys, particularly over-the-counter non-steroidal anti-inflammatory medicines, commonly known as ibuprofen and naproxen.
Conclusion
It is estimated that 20 million Americans have CKD. Those with CKD are classified into five main stages of the disease, based on the percent of their kidney function they still have.For most people, CKD is a “silent disease” that can only be detected by blood tests and a follow-up appointment with your doctor. Proactive treatment strategies include determining your level of kidney function and then implementing a plan to slow down the progression of kidney disease. Working closely with your healthcare provider, you will develop a treatment plan that will help you save your kidneys… and also save your life!
About the Author
Philip Tuso, MD, is a nephrologist in Lancaster, CA. He is also founder of a non-profit organization called the Foundation to Improve Renal Nutrition (FIRN), whose mission is to eliminate malnutrition in dialysis. He has recently published two books, Save Your Kidneys, and How Do I Survive on Hemodialysis?, which are available as free e-books on the foundation's website at: (www.firnav.org/).
Last Updated February 2007