Kidney Health and Kidney Disease Basics

Written by Shannon Johnson | Published on July 9, 2012
Medically Reviewed by George Krucik, MD

What is Kidney Disease?

The kidneys are twin, fist-size organs located at the bottom of the rib cage on either side of the spine. They perform several functions, the most important of which is filtering waste products, excess water, and other impurities out of the blood. These waste products are stored in the bladder and later expelled from the body as urine.

In addition, the kidneys regulate pH, salt, and potassium levels in the body, and they produce hormones that regulate blood pressure and control the production of red blood cells. The kidneys are also responsible for activating a form of vitamin D that helps the body absorb calcium to build bones and modulate muscle function.

he kidneys’ main function is to remove waste products from your blood through urine.

Kidneys are essential to having a healthy body.

Kidney disease occurs when one or more conditions damage your kidneys, keeping them from operating properly. This can lead to health problems including high blood pressure, weak bones, nerve damage, and poor nutritional health.

Illnesses such as diabetes, high blood pressure, and a host of other chronic conditions can cause kidney disease. Kidney disease that gets worse can cause your kidneys to completely fail, which ultimately will require dialysis (a medical procedure) to clean your blood.

According to the National Kidney Foundation, 26 million American adults have kidney disease (NKF).

Types and Causes of Kidney Disease

Chronic Kidney Disease

The most common form of kidney disease ischronic kidney disease, caused by high blood pressure. Because the kidneys are constantly processing the body’s blood supply, they are exposed to about 20 percent of the total blood volume of the body every minute.

High blood pressureis dangerous for the kidneys because it can lead to increased pressure on the glomeruli, which are the functional units of the kidney. In time, this high pressure compromises the filtering apparatus of the kidney, and kidney function begins to decline.

Eventually, kidney function will deteriorate to the point where the kidney can no longer properly perform its job, and a person will be required to go on dialysis. Dialysis filters fluid and wastes out of the blood, but it is not a long-term solution when the kidneys stop functioning. Eventually, kidney transplant may be an appropriate next move, but each circumstance will be different.

Diabetesis also a major cause of chronic kidney disease. Over time, uncontrolled blood sugar will damage the functional units of the kidney, leading to kidney failure.

Kidney Stones

One other common kidney problem is kidney stones. Minerals and other substances in the blood crystallize in the kidneys, forming solid particles (stones) that usually pass out of the body with urine. Passing kidney stones can be extremely painful but rarely causes significant problems.

Glomerulonephritis

Glomerulonephritis is an inflammation of the glomeruli, microscopic structures inside the kidneys that perform the actual filtration of the blood. Glomerulonephritis can be caused by infections, drugs, congenital abnormalities, and autoimmune disease. This condition often gets better on its own or is responsive to immunosuppressive medications.

Polycystic Kidney Disease

Polycystic kidney disease is a genetic disorder that causes many cysts—round sacs of fluid—to grow inside and on the surfaces of the kidneys. These cysts can interfere with kidney function. (Individual kidney cysts are fairly common and almost always harmless; polycystic kidney disease is a separate, more serious condition.)

Urinary Tract Infections

Urinary tract infections (UTIs) are bacterial infections of any of the components of the urinary system. Infections in the bladder and urethra are most common. They are easily treatable and cause few long-term effects. However, if left untreated, these infections could spread to the kidneys and lead to kidney failure. A kidney infection is also known as pyelonephritis.

Symptoms of Kidney Disease

Kidney disease is a condition that can easily go unnoticed until the symptoms become severe.

The following symptoms are the early warning signs that you might be developing kidney disease:

  • fatigue
  • trouble concentrating
  • poor appetite
  • problems sleeping
  • muscle cramping
  • swollen feet/ankles
  • puffiness around eyes in morning
  • dry, scaly skin
  • increased urination, especially during the late evening

Severe symptoms that could indicate that your kidney disease is progressing into kidney failure include:

  • nausea
  • vomiting
  • loss of appetite
  • changes in urine output
  • fluid retention
  • anemia
  • decreased sex drive
  • sudden rise in potassium levels (hyperkatemia)
  • decreased immune response
  • inflammation of sac around heart—pericarditis

Risk Factors for Developing Kidney Disease

Certain people run a higher risk of developing kidney disease. Diabetes is the leading cause of kidney disease—44 percent of people on dialysis have kidney failure caused by diabetes (NKDEP). Other risk factors include:

  • high blood pressure
  • other family members with chronic kidney disease
  • being elderly
  • belonging to a demographic with a history of high diabetes rates and high-blood pressure rates such as African and Hispanic Americans, Asians, American Indians and people from the Pacific Islands.

How Is Kidney Disease Diagnosed?

Your doctor will first determine if you belong in any of the high-risk groups. Doctors will then have a choice of different methods to use to test whether or not your kidneys are functioning properly including:

Glomerular Filtration Rate (GFR)

This test will measure level of kidney function and determine the stage of kidney disease.

Ultrasound or CT Scan

This will give your doctor a clear picture of your kidneys and urinary tract. It will also let your doctors know if your kidneys are too small or large and if any tumors or structural problems are present.

Kidney Biopsy

This test will allow doctors to see what type of kidney disease you have and how much damage has occurred. The doctor will remove a small piece of tissue from your kidney while you are sedated.

Urine Test

Your doctor may order a urine test to look for albumin. This is a protein that can be passed into urine when your kidneys are damaged.

Blood Creatinine Test

Creatinine is a released into the blood when creatine, a molecule stored in muscle, is broken down. If your kidney is not functioning as it should, the levels of creatinine in your blood will increase.

Treating Your Kidney Disease

Treating kidney disease usually focuses on controlling the underlying cause of the kidney disease. This means your doctor will help you better manage your blood pressure, blood sugar, and cholesterol levels.

Drugs and Medication

Your doctor will either prescribe ACE inhibitors (like Zestril, ramparil or Altace) or ARBs (like Avapro and Benicar), which are both blood pressure medications that can slow the progression of kidney disease. They often prescribe these medications even if you do not have high blood pressure to preserve kidney function.

You may be treated with cholesterol drugs like Vytorin to reduce blood cholesterol levels and to maintain kidney health. Depending on your symptoms, your doctor may also prescribe drugs to relieve swelling and also to treat anemia or low red-blood-cell levels.

Dietary and Lifestyle Changes

Dietary changes are just as important as any medications you would take. This is because the causes of kidney disease are mostly lifestyle diseases, or those that are preventable with a healthy lifestyle. Your doctor may recommend you:

  • control diabetes through insulin injections and frequent monitoring
  • cut back on cholesterol
  • cut back on salt
  • choose heart-healthy diet including fresh fruits, fresh veggies, whole grains and low fat dairy
  • limit alcohol consumption
  • increase physical activity
  • lose weight
  • quit smoking

Dialysis and Kidney Disease

Dialysis is an artificial method of filtering the blood and is used when someone’s kidneys have failed or are close to failing. Many people with late-stage kidney disease must go on dialysis either permanently or until a donor kidney for transplantation can be found.

Types of Dialysis

There are two types of chronic dialysis: hemodialysis and peritoneal dialysis.

Hemodialysis

In hemodialysis, the blood is pumped through a special machine that filters out waste products and fluid. Hemodialysis is most commonly done during three sessions per week—each lasting three to five hours long—in a hospital, dialysis center, or at home, but it can also be done in shorter, more frequent sessions.

Several weeks or months before starting dialysis, most patients will have an artery and a vein surgically joined, typically in the forearm. This larger blood vessel is called a fistula, and it allows routine access to high blood flow by accessing an artery instead of a vein. Over time, the vein that is connected to the artery will begin to function more like an artery, and the access point for dialysis will be effective. An implanted tube, called an arteriovenous graft, can also be used for the same purpose if an artery and vein cannot be joined.

The most common side effects of hemodialysis are low blood pressure, muscle cramps, and itching.

Peritoneal Dialysis

In peritonealdialysis, the peritoneum—the membrane of blood vessels lining the abdomen—stands in for the kidneys. A tube is implanted and used to fill the abdomen with a fluid called dialysate. Waste products in the blood flow from the peritoneum into the dialysate, which is then drained from the abdomen.

There are two forms of peritoneal dialysis:continuous ambulatory peritoneal dialysis, in which the abdomen is filled and drained several times during the day, and continuous cycler-assisted peritoneal dialysis, which uses a machine to cycle the fluid in and out of the abdomen at night while the patient sleeps.

The most common side effects of peritoneal dialysis are infections of the abdominal cavity or the site where the tube was implanted, weight gain, and hernia.

Dialysis Complications

In addition, people on either form of dialysis still often experience complications caused by kidney failure such as anemia, bone weakening, and swelling or fluid accumulation in the heart or lungs.

Dialysis-related Amyloidosis

In this condition, proteins are deposited on joints and tendons, causing pain and stiffness of the joints. Dialysis-related amyloidosis is common in people who have been on dialysis for five years or more

What Is the Long-Term Outlook for Kidney Disease Diagnosis

Once diagnosed kidney disease will normally not go away. The best way to maintain kidney health is to incorporate a healthy lifestyle and follow your doctor’s advice. Kidney disease can worsen and ultimately lead to kidney failure.

Kidney failure is when your kidneys are barely working or not working at all. This is managed by dialysis. Dialysis involves the use of a machine to filter waste from your blood. In some cases of kidney failure, your doctor will recommend a kidney transplant. Left untreated, kidney failure can result in death.

Tips to Prevent Kidney Disease

Some risk factors for kidney disease—such as age, race, or family history—are not possible to control, but there are measures you can take to help avoid chronic kidney disease and kidney stones.

Control Blood Sugar

If you’re diabetic, control your blood sugar. High blood-sugar levels damage the small blood vessels in the kidneys as well as the rest of the body.

Control Blood Pressure

Keep your blood pressure below 130/80 mm Hg.High blood pressure also damages these delicate blood vessels in the kidneys.

Reduce Salt Intake

Too much sodium/salt intake increases blood pressure. High blood pressure causes chronic kidney disease.

Quit Smoking

One of the many consequences of smoking is kidney damage.

Be Careful with OTC Drugs

Follow dosage instructions for over-the-counter medications. Taking too much aspirin, acetaminophen, or ibuprofen can cause kidney damage. If normal doses of these medications are not effective at controlling pain, see a doctor.

Get Tested

Ask your doctor about getting a blood test for kidney problems. Kidney problems generally do not cause symptoms until they have progressed relatively far. A “basic metabolic panel” (BMP) is a standard blood test that is commonly ordered as part of a routine medical exam or physical. Part of what a BMP is for is to test for creatinine or urea—chemicals that leak into the blood when the kidneys are not working properly. A BMP can detect issues early, when they are easier to treat. If you are diabetic or have heart disease, high blood pressure, or another kidney disease risk factor, you should be tested annually.

Drink Plenty of Water

Dehydration can cause kidney damage. In addition, drinking water leads to frequent urination, which can help expel kidney stones before they grow large enough to cause severe pain as they pass through.

Limit Certain Foods

Different chemicals in your diet can contribute to certain types of kidney stones. These include:

  • excessive sodium
  • animal protein
  • citric acid, found in citrus fruits such as oranges, lemons, and grapefruits
  • oxalate, a chemical found in rhubarb, beets, okra, spinach, sweet potatoes, tea, and chocolate

Normally, you shouldn’t avoid these foods completely, as many of them are rich in beneficial vitamins and nutrients. If you’ve had kidney stones, your doctor can analyze your particular type of stone and offer advice about adjusting your diet.

Ask About Calcium

Consult a doctor before taking a calcium supplement. Calcium supplements have been linked to an increased risk of kidney stones, though reducing intake of oxalic acid and increasing citric acid in the diet are more important to reducing the incidence of kidney stones than reducing calcium stones.

5 Questions to ask Your Doctor

If you’re going to see a doctor about a kidney ailment, here are five important questions to ask.

What can I do to prevent another kidney stone?

People who have had one kidney stone are at higher risk for another. If you pass a kidney stone in your urine, try to collect it in a strainer so your doctor can analyze the type of chemical it contains. Depending on the type of stone, you may need to alter your diet, drink large amounts of water, or take specific medications.

Can I pass polycystic kidney disease on to my children?

Polycystic kidney disease is a genetic disorder that comes in two forms: autosomal dominant, which is responsible for about 90 percent of cases, and autosomal recessive. If you have the dominant form, your children have a 50 percent chance of developing the disease whether or not the other parent has it too. If you have the recessive form, your children cannot develop the disease unless both parents have it, and even then there is only a 25 percent chance. A simple genetic test can determine which form you have.

When will I need dialysis?

Most kinds of kidney disease get progressively worse and will eventually result in kidney failure, requiring dialysis or a transplant. Dialysis can require major changes in lifestyle, so it may be helpful to plan for that eventuality. Most people with kidney failure start dialysis when their kidneys have lost 85 to 90 percent of their function capabilities.

Am I a good candidate for a transplant?

Before you can begin looking for a donor kidney, you must undergo a series of exams to determine if you are a viable transplant recipient. Doctors will run tests on your heart, lungs, and other organs to make sure your body can handle a transplant, and they will evaluate your mental health as well.

What happens if I donate my kidney?

The best candidates for kidney donation are close relatives, which means that if you have a family member with kidney failure, you may be asked to donate one of your kidneys. It is possible to lead a completely normal life with one kidney, and donors are not known to have a higher risk of kidney disease or a lower life expectancy than normal healthy adults. However, as with any surgery, there are risks associated with the kidney removal procedure itself. Before you are allowed to donate a kidney, your health will be evaluated to make sure your body can handle the process.

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