The kidneys are small, bean-shaped organs, but they perform several essential jobs that keep the body healthy. They filter waste and extra fluid from the blood, help control blood pressure, maintain mineral balance, support healthy red blood cell production, and contribute to strong bones.
When the kidneys become damaged or lose their ability to work properly, kidney disease can develop. Some kidney problems appear suddenly, while others develop slowly over many years. Chronic kidney disease (CKD) is particularly important because it may cause few noticeable symptoms in its early stages.
What Is Kidney Disease?
Kidney disease is a general term for conditions that damage the kidneys or interfere with their ability to work properly. One of the most important forms is chronic kidney disease, which means kidney damage or reduced kidney function continues for at least three months.
The problem may affect the kidney's filtering system, blood vessels, tissues, or the urinary system. When the kidneys cannot filter the blood effectively, waste products and excess fluid can build up in the body. As kidney function declines, problems can also develop with blood pressure, red blood cells, bones and the body's mineral balance.
Kidney problems can include chronic kidney disease, acute kidney injury, kidney stones, kidney infections, inherited kidney conditions and diseases that affect the kidney's filtering units.
What Causes Kidney Disease?
There are many possible causes of kidney disease, but some are much more common than others.
Diabetes is one of the leading causes because persistently high blood sugar can damage the tiny blood vessels that filter blood inside the kidneys. High blood pressure can also damage these vessels over time.
Other possible causes and risk factors include:
- Heart disease or heart failure
- Obesity
- Family history of kidney disease
- Previous acute kidney injury
- Kidney stones or repeated urinary infections
- Autoimmune diseases such as lupus
- Inherited conditions such as polycystic kidney disease
- Problems that block normal urine flow
- Certain infections
- Some medicines or long-term exposure to substances that can harm the kidneys
Age can also increase the risk, although kidney disease can occur in people of any age. Smoking and some lifestyle factors may further increase kidney risk.
Kidney Disease Symptoms
One of the most concerning features of chronic kidney disease is that kidney disease symptoms may not appear until the condition has become more advanced.
As kidney function decreases, possible symptoms include:
- Persistent tiredness or weakness
- Swelling around the ankles, feet or legs
- Changes in how often you urinate
- Foamy or unusually bubbly urine
- Loss of appetite
- Nausea or vomiting
- Itchy or dry skin
- Muscle cramps
- Trouble sleeping
- Difficulty concentrating
- Shortness of breath
- Unexplained weight loss
These symptoms are not specific to kidney disease and can occur with many other health problems. Testing is therefore more reliable than symptoms alone for detecting chronic kidney problems.
How Is Kidney Disease Diagnosed?
Kidney disease diagnosis usually begins with simple blood and urine tests.
The most important blood test is the estimated glomerular filtration rate (eGFR). It estimates how effectively the kidneys are filtering waste from the blood. Normal value is typically 90 mL/min/1.73 m² or higher for healthy adults.
A urine test called the urine albumin-to-creatinine ratio (uACR) checks for albumin, a type of protein that can leak into the urine when the kidney's filtering system is damaged.
Depending on the suspected cause, doctors may also recommend:
- Blood pressure measurement
- Ultrasound or other kidney imaging
- Additional blood or urine tests
- Genetic testing in selected cases
- Kidney biopsy when the cause is unclear or specific information is needed
For chronic kidney disease, reduced kidney function or signs of kidney damage generally need to persist for at least three months.
Stages of Chronic Kidney Disease
Doctors use kidney disease stages to understand how much kidney function has been lost and to guide treatment.
Chronic kidney disease is generally classified into five stages, based largely on eGFR:
- Stage 1: Kidney damage is present, but filtration may still be normal or near normal.
- Stage 2: Mild reduction in kidney function.
- Stage 3: Moderate reduction in kidney function.
- Stage 4: Severe reduction in kidney function.
- Stage 5: Very severe loss of kidney function, also known as kidney failure.
Doctors also consider albumin levels in urine and the underlying cause of kidney disease. Therefore, a stage number alone does not tell the entire story about a person's kidney health.
Kidney Disease Treatment
There is no single kidney disease treatment because treatment depends on the cause and stage of the condition.
For chronic kidney disease, treatment generally aims to slow further damage and manage the condition responsible for it. Controlling high blood pressure and blood sugar is particularly important when hypertension or diabetes is contributing to kidney damage.
Doctors may prescribe medicines that help control blood pressure and cholesterol, reduce protein loss through the urine, or slow the progression of certain forms of CKD. They often suggest diuretics and SGLT2 inhibitors to reduce the risk of disease progression. Some people may also need treatment for anemia, mineral imbalances or other complications.
Nutrition can also play an important role. Depending on kidney function and laboratory results, a person may need to adjust sodium (2000mg/day), potassium, phosphorus, protein or fluid intake. These changes should be individualized rather than following a restrictive kidney diet without professional guidance.
Some pain medicines, particularly certain nonsteroidal anti-inflammatory drugs (NSAIDs), can harm the kidneys, especially when used frequently or in people who already have kidney problems. It is important to ask a healthcare professional before regularly using such medicines.
How Can Kidney Disease Be Prevented?
Not every kidney condition can be prevented, but several steps can reduce the risk of kidney damage. Kidney disease prevention starts with controlling the health conditions that commonly damage the kidneys.
Helpful measures include:
- Keep blood pressure within a healthy range.
- Manage diabetes and blood glucose carefully.
- Maintain a healthy body weight.
- Eat a balanced diet with appropriate amounts of salt.
- Stay physically active.
- Avoid smoking.
- Use medicines responsibly and avoid unnecessary kidney-damaging drugs.
- Drink an appropriate amount of fluid for your individual health needs.
- Get tested if you have diabetes, high blood pressure, heart disease or a family history of kidney disease.
Regular testing is particularly important because early kidney disease often produces no obvious warning signs.
When Kidney Disease Becomes Kidney Failure?
When kidney function becomes severely reduced, the body can no longer adequately remove waste and excess fluid. This is known as kidney failure.
At this stage, treatment may include dialysis, which uses a machine or alternative processes to perform some of the kidneys' filtering work. For suitable patients, a kidney transplant may provide another treatment option.
However, not everyone with chronic kidney disease develops kidney failure. Early diagnosis and appropriate treatment can help slow progression and protect remaining kidney function.
Final Takeaways
Kidney disease can be difficult to recognize first because it may develop quietly. By the time symptoms become obvious, kidney function may already have declined significantly.
The good news is that simple blood and urine tests can help identify kidney problems, particularly in people with diabetes, high blood pressure or other risk factors.
Protecting your kidneys is closely connected with protecting your overall health. Begin Health Life suggests, managing blood pressure, controlling diabetes, staying active, maintaining a healthy weight and seeking medical care early to help preserve kidney function for longer.