According to the CDC, chronic kidney disease (CKD) affects approximately 15% of the U.S. adult population, or about 37 million people. And yet, it is likely underdiagnosed, which means many people don’t know they are at risk of this severe kidney condition.
What is Chronic Kidney Disease?
Chronic kidney disease is a progressive condition that causes the kidneys to function less effectively over time. There are different types of disease, including disease caused by external factors (lifestyle habits, such as diets) as well as polycystic kidney disease, which refers to kidney cysts that affect kidney function.
Doctors measure kidney function by calculating the glomerular filtration rate (GFR), which refers to how much blood the kidneys filter each minute. GFR is calculated using a range of factors, including age and race. Normal GFR is about 60 or higher. Anything lower than 60 indicates kidney impairment. A GFR of 15 or below indicates kidney failure.
Aldosterone plays a significant role in many cases of kidney disease. Aldosterone is a hormone in the body’s renin-angiotensin-aldosterone system (RAAS) and it tells the kidneys to hold onto more water and salt, causing blood pressure to rise. Too much aldosterone can cause high blood pressure. This increase in blood pressure and aldosterone’s other effects (such as enhanced oxidative stress, inflammation and fibrosis) can cause kidney damage. Specifically, these negative effects put excess pressure on the kidneys, especially as the disease progresses over several years.
Who is Likely to Have Chronic Kidney Disease?
People with an increased risk of developing chronic kidney disease share some of the following conditions or characteristics:
- Hypertension (high blood pressure)
- Heart disease
- A family history of kidney disease
- African, Native or Asian American heritage
Heart disease, hypertension and diabetes are among the great risk factors for kidney disease. In fact, these conditions are the leading causes of chronic kidney disease, partly because they are prevalent diseases.
What are the Causes of Chronic Kidney Disease?
Hypertension, diabetes and glomerulonephritis, or inflammation of the tiny filters in the kidneys, are considered the leading conditions that cause, worsen, or increase the risk of kidney damage. People with heart disease are also more likely to develop CKD. Hypertension and diabetes, in particular, can damage the blood vessels in the kidney, making it harder for the kidney to filter blood successfully.
What are the Symptoms of Chronic Kidney Disease?
In the early stages of kidney disease, patients often don’t experience symptoms. As a result, it often goes unnoticed and is underdiagnosed.
Symptoms are most common when someone reaches end-stage renal (kidney) disease, meaning that kidney function is severely impaired. Some of these symptoms include:
- Itchy skin
- Changes in urination frequency
- Treatment-resistant hypertension (high blood pressure that is difficult to treat)
- Swelling (edema) due to fluid buildup
- Anemia (low red blood cell count)
Many of these symptoms occur because the kidneys cannot properly filter blood, fluids and nutrients. For example, edemas can happen because the kidney loses the ability to drain excess fluids. These fluids then build up in the body. The kidneys may also be unable to keep a healthy balance of nutrients in the blood, leading to itchy skin.
How is Chronic Kidney Disease Diagnosed?
A kidney disease diagnosis usually involves some or most of the following tests and procedures:
- Physical exam. A doctor will check for any external symptoms that might indicate CKD. They will also review a patient’s medical history to determine if there is a family history of kidney disease.
- Urine tests. These tests look for albuminuria (the presence of a protein called albumin in the urine). Normally, the kidneys prevent albumin from entering the bloodstream, but some albumin can pass into the urine when someone has reduced kidney function.
- Blood tests. Healthy kidneys filter waste products from the blood. A blood test that reveals high levels of waste products (such as a chemical called creatinine) in the blood could indicate kidney impairment.
- Imaging. In some cases, a doctor may need to see a patient’s kidney to look for any structural abnormalities affecting its ability to function.
- Kidney biopsy. A doctor may need to take a sample of kidney tissue for testing. This test can help identify any specific abnormalities in the kidney.
While these tests can help detect and confirm a diagnosis, the hallmark signs are creatinine in the blood and albumin in urine.