The kidneys are the Rodney Dangerfield of major organs—they usually get no respect. Most people don’t appreciate their importance until something goes wrong. And increasingly things are going wrong with the kidneys of Americans, thanks largely to the rise in hypertension and diabetes resulting from the ongoing obesity epidemic.
Kidney disease basics
It’s estimated that 26 million Americans—about one in nine adults—have chronic kidney disease (CKD), and most don’t know it. A 2011 study from Vanderbilt University in Nashville found that even among people undergoing treatment for CKD, one-third didn’t know they had a serious disease. CKD mostly affects people over 60; blacks, Hispanics and people with a family history of the disease are at higher risk. Though it can’t be cured, CKD is usually preventable. (Note: CKD doesn’t include kidney stones.)
CKD usually stays under the radar because it has no symptoms until kidney function is very impaired, and even then there may be few, if any, symptoms. It varies greatly in severity and can take many years to progress. And when symptoms do eventually develop, they tend to be general and varied, such as fatigue, weakness, loss of appetite, nausea, itchy skin, dizziness, shortness of breath, increased need to urinate and swelling in the ankles and elsewhere. A recent study from the University of Maine also linked reduced kidney function to cognitive decline.
Over time, CKD impairs the kidneys’ ability to do their essential tasks, notably filtering the blood to remove impurities and waste products, which are excreted in urine; maintaining the acid/alkaline balance of the body’s fluids (by regulating electrolytes such as sodium, calcium and potassium); adjusting fluid balance; releasing hormones that regulate blood pressure and the production of red blood cells; and converting vitamin D into its active form.
As kidney function worsens, waste products build up in the bloodstream, fluid balance goes out of whack and every cell in the body is affected. Potential complications include:
- bone loss,
- nerve damage,
- edema (excess fluid in tissues),
- high blood pressure (hypertension causes CKD and vice versa),
- heart disease,
- and certain digestive disorders.
Left untreated, CKD may lead to kidney failure, requiring dialysis or a kidney transplant.
Diabetes and hypertension are responsible for up to two-thirds of all cases of CKD. That’s why preventing or controlling high blood pressure and blood sugar is key to preventing CKD and, if it develops, to slowing or preventing its progression. If you have these diseases, your kidney function should be monitored. Simple blood and urine tests can detect kidney impairment.
A kidney-friendly diet?
If you’ve been diagnosed with CKD, your health care provider or a registered dietitian can help you devise an individualized “renal” diet, based on the type and severity of the damage and other factors. This usually involves greatly reducing sodium and limiting three “p”s—protein, phosphorus and potassium. You should obviously avoid high-protein diets, such as Atkins. Though potassium is essential for blood pressure control, it can build up to dangerous levels in your body if your kidneys aren’t functioning well.