Chronic Kidney Disease

What is chronic kidney disease (CKD)?

The main function of the kidney is to filter wastes and excess water out of the blood. The kidney also keeps the body’s chemical balance, regulate blood pressure, and control hormone levels that are important for red blood cell production. CKD is a medical condition in which the damaged kidney is slowly and progressively losing its normal functions.  If left uncontrolled, CKD can lead to heart failure and other life threatening health problems.  The final stage of CKD is kidney failure [also called end-stage renal disease (ESRD)], in which the kidneys do not function anymore and the patient needs dialysis or a kidney transplant.  People of all ages and backgrounds can develop CKD.  However, there are steps you can take (including making lifestyle changes) to slow down or control CKD.

Symptoms of CKD

Because the two kidneys in the body lose their function slowly in CKD, many patients experience no symptoms at early CKD stages. Indeed, many people are not diagnosed with CKD until they have lost most of the kidney function. The common symptoms at advanced stages, although may also be caused by other illness, include:

• swelling of the feet and hands
• fainting, nausea, and vomiting
• appetite loss and weight loss
• fatigue, drowsiness, and confusion
• sleep problems
• bone, joint, and muscle pain

Diagnosis of CKD

CKD is defined as reduction of kidney function and evidence of kidney damage.  The following medical tests and procedures help doctors to diagnose CKD:

• Blood test:  Blood sample is taken to determine glomerular filtration rate (GFR), an index for kidney function. GFR levels help to determine the stage of CKD (Table 1). If GFR is <60 mL/min/1.73 m2, the kidney function is reduced and CKD is often diagnosed.  Kidney failure is defined as GFR <15 mL/min/1.73 m2. Your doctor will learn more about your kidney condition from other tests also conducted on samples, including blood urea nitrogen (BUN), electrolytes (sodium, potassium, calcium, and phosphorus), creatinine, and blood cell counts.

Table 1.  Stage of CKD

• Urine test.  This test checks the protein level of albumin in the urine sample.  Normally, there is no or very little albumin in the urine. Evidence of kidney damage is defined as >30 mg/g of urine albumin-to-creating ratio (UACR).
• Imaging tests. Ultrasound, x-ray, computed tomography scan (CT scan), and magnetic resonance imaging (MRI) may be performed to assess the structure of the kidneys and determine if there are also other abnormalities in the kidney.  These techniques are noninvasive, safe, reliable, and reproducible, and allow serial measurements.   
• Biopsy: A small piece of the kidney tissue may be sampled to make clear diagnosis for CKD. The kidney sample will be examined under microscope and the cause for CKD may be determined.  Kidney biopsy is usually done with local anesthesia by inserting a long needle through the skin into the kidney.

Risk Factors for CKD

Scientists have identified several factors that can increase the probability of developing CKD.  The major risk factors include:

• Diabetes.
• High blood pressure.
• Coronary heart disease.
• Family history of CKD.
• Obesity.

You cannot change your heredity, but you can take simple steps to improve your lifestyle and lower other your risks of developing CKD. Lifestyle changes have enabled many CKD patients live a full enjoyable life.

Complications of CKD

CKD may cause many complications, and some of them may be life threatening. It is important to note that Patients with early stage of CKD are 20 times more likely to develop cardiovascular disease than to progress to kidney failure. The common complications are:

• Coronary heart disease.
• High blood pressure.
• Increased blood potassium levels (hyperkalemia).
• Heart failure.
• Fluid buildup (edema) in your lungs, arms, and ankles.
• Anemia.
• Bone fractures.

Prevention and Treatment of CKD

CKD is a serious medical condition.  These following steps help to keep your kidneys healthy:

• Monitor blood pressure.  Keep blood pressure in the normal range is an important step to prevent and slow kidney damage.  Angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and beta blockers are the most often used medication to keep blood pressure at or below 130/80 mmHg.
• Control blood glucose.  If you are diabetic, controlling blood glucose level in the target range helps to prevent many complications including CKD.  Read Diabetes for more information which may help to control blood glucose.
• Maintain a healthy body weight.  Overweight and obesity cause many medical problems and make your kidneys work too hard.  Read Obesity for more information about how to control body weight.
• Diuretics.  Your doctor may prescribe diuretics to get rid excess fluid buildup in your body due to CKD.
• Dialysis.  Dialysis is a treatment option for kidney failure.  Your doctor may order hemodialysis or peritoneal dialysis for you.  These procedures remove wastes, chemicals, and extra water from your body. Hemodialysis uses a machine to filter your blood and remove harmful wastes, extra salt, and extra water.  Peritoneal dialysis uses the lining of your belly as the artificial kidney to filter your blood.  Each dialysis method has its advantages and disadvantages.  If you need dialysis, be sure to talk to your doctor about the treatment options.
• Kidney transplantation.  The other treatment option for kidney failure is kidney transplantation. The wait for a donated kidney can be years long. Also, it requires you to take medicines for the rest of your life to suppress immune response after kidney transplantation. Even people who are candidates for a kidney transplant may need dialysis while waiting for a kidney to become available.
• Stop smoking: Smoking can damage blood vessels, raise blood pressure, and increase the risk of developing CKD and other devastating diseases. If you smoke, your doctor may recommend a quit smoking program for you.
• Avoid too much salt. Too much table salt (sodium) can increase raise blood pressure and cause fluid buildup in the lungs, arms, and ankles. Your medical conditions and treatment options determines how much salt you can consume each day. Be sure to talk to your doctor and dietitian about your maximum daily salt intake. 
• Be physically active: Even moderate physical activity is beneficial for your overall health. For prevention of CKD, exercise frequently and stay physically active. If you have CKD, consult your doctor for the physical activities best fit your condition.  
• Eat a better diet.  To prevent CKD, consider the Dietary Approaches to Stop Hypertension (DASH) for an overall eating plan. The DASH diet plan emphasizes fruits, vegetables, and low fat dairy foods. It includes whole grains, poultry, fish, and nuts, but has reduced amounts of fats, red meats, sweets, and sugared beverages. Eating a DASH diet can help decrease high blood pressure and reduce risk of developing CKD.  If you have CKD or kidney failure, talk to your doctor and dietarian about the best diet choice for you, since some CKD medical treatments may need to limit intake of certain food types.
• Supplements.  If you have CKD, always talk to your kidney doctor before taking any over-the-counter medicine, vitamins, or herbal supplements.

CKD Facts

• More than 10 percent of people, or about 26 million, ages 20 years and older in the US have CKD. And millions of others are at increased risk.
• There are 560,000 kidney failure patients in the US who are living on dialysis or with a kidney transplant.
• The estimated annual cost for kidney failure treatment is $40 billion in the US.
• Patients with early stage of CKD are 20 times more likely to develop cardiovascular disease than to progress to kidney failure.
• Early detection and treatment of CKD can prevent the development of heart diseases and other health problems.
• Diabetes, high blood pressure, and family history of kidney disease are major risk factors for developing CKD.
• High blood pressure may cause CKD, and CKD may cause high blood pressure.
• There were 17,000 kidney transplantations in the US in 2011, and 92,000 patients were on the waiting list.