Chronic Kidney Disease

Written by Verneda Lights and Elizabeth Boskey, PhD | Published on July 25, 2012
Medically Reviewed by George Krucik, MD

Overview

Chronic kidney disease (CKD) causes destruction of the kidneys. It is progressive and irreversible.

Your kidneys are an essential part of your body. They have a number of functions:

  • help maintain the balance of minerals and electrolytes such as calcium, sodium, and potassium
  • play an essential role in the production of red blood cells
  • maintain the delicate acid-base balance of the blood
  • excrete water soluble wastes from the body

If the kidneys are damaged, these functions become compromised. In their 2009 Chronic Kidney Disease Surveillance Report, the U.S. Centers for Disease Control found that an estimated twenty-six million Americans have CKD.

What Causes Chronic Kidney Disease?

The most common causes of CKD are high blood pressure and diabetes.

Each kidney contains about one million tiny filtering units called nephrons. Any disease that injures or scars these filtering units can cause kidney disease. Diabetes and high blood pressure can both damage the nephrons.

High blood pressure can also damage the blood vessels of the kidneys, heart, and brain. This is key, because, in general, blood vessel diseases are dangerous to the kidneys. The kidneys are very vascular—meaning they contain lots of blood vessels.

Autoimmune diseases such as lupus can damage blood vessels and can make antibodies against kidney tissue.

Other causes of CKD are varied. Polycystic kidney disease is a hereditary cause of CKD. Glomerulonephritis can be caused by lupus. It can also appear after a streptococcal infection.

Risk Factors for Chronic Kidney Disease

The risk of CKD increases over the age of 65. It runs in families. It is more likely to occur in African-Americans, American Indians, and Asian Americans. Other risk factors for CKD include:

  • cigarette smoking
  • obesity
  • high cholesterol
  • diabetes, both type 1 and 2
  • autoimmune disease
  • obstructive kidney disease – including bladder obstruction caused by benign prostatic hyperplasia
  • atherosclerosis
  • cirrhosis and liver failure
  • narrowing of the artery that supplies the kidney
  • kidney cancer
  • bladder cancer
  • kidney stones
  • kidney infection
  • lupus
  • scleroderma
  • vasculitis
  • vesicoureteral reflux, where urine flows back into the kidney

Recognizing the Symptoms of Chronic Kidney Disease

CKD does not cause any symptoms until about 90 percent of the kidney has been destroyed.

Once the kidney is severely damaged, symptoms of CKD could include:

  • swelling around the eyes (periorbital edema)
  • swelling of the legs (pedal edema)
  • fatigue
  • shortness of breath
  • nausea
  • vomiting, especially in the morning and after eating
  • urine-like odor to the breath
  • bone pain
  • abnormally dark or light skin
  • ashen cast to skin (uremic frost)
  • drowsiness
  • mental cloudiness
  • numbness in the hands and feet
  • restless leg syndrome
  • brittle hair and nails
  • itching
  • weight loss
  • loss of muscle mass
  • muscle twitching and cramps
  • easy bruising and bleeding
  • blood in stools
  • hiccups
  • excessive thirst
  • low level of interest in sex, impotence
  • insomnia
  • sleep apnea

You may also experience the symptoms of any diseases contributing to your kidney problems.

Diagnosis of Chronic Kidney Disease

The diagnosis of CKD begins with a medical history. A family history of kidney failure can raise suspicions. So can a history of high blood pressure or diabetes. However, other tests are needed to confirm a CKD diagnosis.

Complete Blood Count

A complete blood count (CBC) can show anemia. Kidneys produce erythropoietin. This is the hormone that stimulates the bone marrow to produce red blood cells. When the kidney is severely damaged, the ability to produce erythropoietin decreases. This causes the decline in red blood cells known as anemia.

Electrolytes

CKD can affect your electrolyte levels. Potassium may be high and bicarbonate levels may be low. There may be an increase of acid in the blood.

Blood Urea Nitrogen (BUN)

BUN can be elevated when the kidney starts to fail. Normally, the kidney clears products of protein breakdown from the blood. However, after kidney damage, byproducts build up. Urea is one byproduct of protein breakdown. Urea is what gives urine its odor.

Creatinine

As kidney function declines, creatinine increases. This protein is also related to muscle mass.

Parathyroid Hormone (PTH)

The kidney and the parathyroid glands interact through the regulation of calcium and phosphorus. Changes in kidney function affect the release of PTH. This affects calcium levels throughout the body.

When the kidney progresses to end stage renal disease (ESRD), it no longer excretes sufficient phosphorus. Vitamin D synthesis is impaired. Calcium may be released from bone. Over time, this causes bones to become weak.

Renal Flow and Scan

This is an imaging study of kidney function.

Renal Ultrasound

This noninvasive test measures the kidneys and prostate. It gives information about whether an obstruction is present.

Additional tests for CKD include:

  • biopsy of the kidney
  • bone density test
  • abdominal computed tomography (CT) scan
  • abdominal magnetic resonance imaging (MRI)

Treatment of Chronic Kidney Disease

CKD is chronic and irreversible. Treatment focuses on improving the underlying disease.

Treatment can also prevent and manage complications of CKD, such as:

  • fluid overload 
  • congestive heart failure
  • anemia
  • brittle bones
  • weight loss
  • electrolyte imbalance

Control of underlying problems, such as hypertension and diabetes, can slow the rate of kidney damage.

Once kidney function is reduced to 10 percent or less, symptoms become obvious. At this point, there may be a need for dialysis or a kidney transplant.

When the kidneys are clearly beginning to shut down, it is called end stage renal disease. Treatment for CKD/ ESRD includes:

  • smoking cessation
  • low-fat meals
  • salt restriction to control blood pressure and prevent fluid overload
  • protein restricted diet, with adequate calories to maintain weight
  • potassium restricted diet
  • adequate exercise
  • blood purification via dialysis
  • kidney transplantation
  • fluid restriction to prevent fluid overload
  • carbohydrate restriction, for patients with diabetes
  • controlling diabetes
  • blood pressure control
  • iron and vitamin supplements to manage anemia
  • erythropoietin injections to stimulate red blood cell production.
  • calcium and vitamin D supplements
  • phosphate binders
  • stool softeners for constipation
  • antihistamines for itching

People with CKD/ESRD may be more susceptible to infection. It is recommended that they get the following vaccinations:

  • pneumococcal
  • hepatitis B and A
  • influenza
  • H1N1 (swine flu)

Prevention of Chronic Kidney Disease

CKD cannot always be prevented. However, controlling conditions like high blood pressure and diabetes can help.

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