Chronic kidney disease (CKD) is the progressive and irreversible destruction of the kidneys.
Your kidneys are essential parts of your body. They have several functions, including:
- helping maintain the balance of minerals and electrolytes in your body, such as calcium, sodium, and potassium
- playing an essential role in the production of red blood cells
- maintaining the delicate acid-base balance of your blood
- excreting water-soluble wastes from your body
Damaged kidneys lose their ability to perform these functions. The U.S. Centers for Disease Control (CDC) estimates that at least 20 million Americans have CKD.
The most common causes of CKD are high blood pressure and diabetes.
Each kidney contains about 1 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 your nephrons.
High blood pressure can also damage the blood vessels of your kidneys, heart, and brain. This is key because blood vessel diseases are generally dangerous to your kidneys. The kidneys are highly vascularized, meaning they contain lots of blood vessels.
Autoimmune diseases such as lupus can damage blood vessels and can make antibodies against kidney tissue.
There are various other causes of CKD. Polycystic kidney disease is a hereditary cause of CKD. Glomerulonephritis can be due to lupus. It can also appear after a streptococcal infection.
The risk of CKD increases for those over the age of 65. It runs in families. It’s more likely to occur in African-Americans, Native Americans, and Asian-Americans. Other risk factors for CKD include:
- cigarette smoking
- high cholesterol
- diabetes (types 1 and 2)
- autoimmune disease
- obstructive kidney disease, including bladder obstruction caused by benign prostatic hyperplasia (BPH)
- cirrhosis and liver failure
- narrowing of the artery that supplies your kidney
- kidney cancer
- bladder cancer
- kidney stones
- kidney infection
- systemic lupus erythematosus (SLE)
- vesicoureteral reflux, which occurs when urine flows back into your kidney
CKD doesn’t cause any symptoms until most of your kidney is destroyed. Once the kidney is severely damaged, the symptoms of CKD can include:
- swelling around your eyes, which is called periorbital edema
- swelling of your legs, which is called pedal edema
- shortness of breath
- vomiting, especially in the morning and after eating
- a urine-like odor to your breath
- bone pain
- abnormally dark or light skin
- an ashen cast to your skin, which is called uremic frost
- mental cloudiness
- numbness in your hands and feet
- restless leg syndrome
- brittle hair and nails
- weight loss
- a loss of muscle mass
- muscle twitching and cramps
- easy bruising and bleeding
- blood in your stools
- excessive thirst
- low level of interest in sex, impotence
- sleep apnea
You may also have the symptoms of any diseases that are contributing to your kidney problems.
The diagnosis of CKD starts with a medical history. A family history of kidney failure can raise suspicions, as can a history of high blood pressure or diabetes. However, other tests are necessary to confirm that you have CKD.
Complete Blood Count (CBC)
A complete blood count (CBC) can show anemia. Your kidneys make erythropoietin, which is a hormone. This hormone stimulates your bone marrow to make red blood cells. When your kidney is severely damaged, your ability to make erythropoietin decreases. This causes a decline in red blood cells known as anemia.
CKD can affect your electrolyte levels. Potassium may be high and bicarbonate levels may be low if you have CKD. There may also be an increase of acid in the blood.
Blood Urea Nitrogen (BUN)
Blood urea nitrogen (BUN) can become elevated when your kidney starts to fail. Normally, your kidney clears the products of protein breakdown from your blood. However, after kidney damage, these byproducts build up. Urea is one byproduct of protein breakdown. Urea is what gives urine its odor.
As kidney function declines, your 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. A change in kidney function affects the release of PTH. This affects calcium levels throughout your body.
When your kidney progresses to end-stage renal disease (ESRD), it no longer excretes enough phosphorus and it impairs vitamin D synthesis. Your bones may release calcium. This causes your bones to become weak over time.
Renal Flow and Scan
This is an imaging study of kidney function.
This noninvasive test provides images to help determine whether there’s an obstruction.
Additional tests for CKD include:
- a kidney biopsy
- a bone density test
- an abdominal CT scan
- an abdominal MRI
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
- brittle bones
- weight loss
- electrolyte imbalance
Control of underlying problems, such as hypertension and diabetes, can slow the progress of kidney damage.
Once your kidney function reduces to 10 percent or less, the symptoms become obvious. At this point, you may need dialysis or a kidney transplant.
ESRD occurs when your kidneys clearly begin to shut down. The treatment for CKD and ESRD includes:
- quitting smoking if you smoke
- restricting fat in your diet
- restricting salt in your diet to control blood pressure and prevent fluid overload
- restricting protein in your diet (but still getting adequate calories to maintain your weight)
- restricting potassium in your diet
- getting adequate exercise
- getting dialysis to purify your blood
- getting a kidney transplant
- restricting your fluids to prevent fluid overload
- restricting carbohydrates if you have diabetes
- controlling diabetes if you have it
- controlling your blood pressure
- taking iron and vitamin supplements to manage anemia
- getting erythropoietin injections to stimulate the production of red blood cells
- taking calcium and vitamin D supplements
- taking phosphate binders
- taking stool softeners for constipation
- taking antihistamines for itching
You may be more susceptible to infection if you have CKD or ESRD. Doctors recommend that you get the following vaccinations:
- pneumococcal vaccine
- hepatitis B vaccine
- influenza vaccine
- H1N1 (swine flu) vaccine
You can’t always prevent CKD. However, controlling conditions like high blood pressure and diabetes can help. You should get regular screenings for CKD if you’re at high risk. Getting an early diagnosis of CKD can help slow its progress.