Is Renal Failure the Same as Kidney Failure? Understanding the Terms, Differences, and What They Mean for Your Health
Explore what renal failure and kidney failure mean, how they compare, and what each term means for diagnosis, treatment, and your overall kidney health.
Is Renal Failure the Same as Kidney Failure?
When you or your loved one receives a medical report mentioning renal failure or kidney failure, confusion about whether these terms refer to the same condition is common. The good news: renal failure and kidney failure mean exactly the same thing. Renal simply means ‘of the kidneys.’ In clinical settings, these names are used interchangeably to describe the situation where the kidneys are no longer able to filter wastes and maintain fluid and electrolyte balance as they should.
Understanding the Kidneys’ Role
Your kidneys are two bean-shaped organs playing a vital part in your health. They filter waste and extra fluid from your blood, maintain electrolyte balance, regulate blood pressure, and produce hormones that are essential for making red blood cells and keeping your bones strong.
- Location: On either side of your spine, just below the rib cage
- Main functions:
- Filtering waste products and extra water from your blood to make urine
- Balancing important elements like sodium, potassium, and calcium
- Regulating blood pressure via fluid balance and certain hormone production
What Does ‘Renal’ Mean?
The word renal comes from the Latin term for kidney. So, ‘renal failure’ is simply the medical phrase for what most people call ‘kidney failure.’ For example, a condition called acute renal failure may also be referred to as acute kidney failure or acute kidney injury (AKI).
Are There Differences Between Renal Failure and Kidney Failure?
No. Both terms describe the same condition: a state where the kidneys are not filtering wastes and excess fluids efficiently. Healthcare professionals sometimes use both terms in different contexts but always mean the same physiological failure.
- Renal failure = Kidney failure
- Both mean the kidneys cannot keep up with the body’s filtration needs
- Other common terms: “end-stage renal disease” (ESRD), “end-stage kidney disease” (ESKD), especially when referencing advanced stages
Renal Failure vs. Kidney Disease
While ‘renal failure’ and ‘kidney failure’ are identical, kidney disease is a broader term. Kidney disease describes any state where the kidneys don’t function optimally—but not necessarily to the extent of complete failure.
- Kidney disease: Encompasses a range of abnormalities in kidney function, from mild to severe.
- Renal/kidney failure: Refers specifically to severely decreased kidney function, usually requiring urgent medical intervention.
Traditionally, ‘chronic renal failure’ and ‘chronic kidney disease’ were used interchangeably, but clinicians now prefer ‘kidney disease’ to prevent confusion, since ‘failure’ implies a complete lack of function which may not always be the case.
Stages of Kidney Disease
Chronic kidney disease (CKD) progresses from mild dysfunction to complete failure. Doctors classify CKD by ‘stages’ based on glomerular filtration rate (GFR):
| Stage | Description | GFR (mL/min) |
|---|---|---|
| 1 | Normal or high kidney function | >90 |
| 2 | Mildly decreased | 60–89 |
| 3a | Mild to moderately decreased | 45–59 |
| 3b | Moderate to severely decreased | 30–44 |
| 4 | Severely decreased | 15–29 |
| 5 | Kidney failure (ESKD/ESRD) | <15 |
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Note: Only stage 5 is considered kidney (renal) failure.
Types of Kidney (Renal) Failure
Kidney failure can be classified based on how quickly it develops and how long it lasts. There are two main forms:
- Acute Kidney (Renal) Failure (AKI): Sudden loss of kidney function, usually within hours or days.
- Chronic Kidney (Renal) Failure (CKD): Gradual decline in kidney function over months or years.
Acute Renal (Kidney) Failure (Acute Kidney Injury, AKI)
Acute renal failure (or AKI) is when kidney function falls abruptly. The condition often occurs in hospitalized patients who are severely ill, post-surgical, or dealing with significant fluid loss or infection. Causes include:
- Severe dehydration or blood loss
- Serious infections (sepsis)
- Certain medications (e.g., strong antibiotics, NSAIDs, or contrast dyes)
- Acute inflammation or damage (e.g., glomerulonephritis)
- Urinary tract blockage (e.g., kidney stones)
Unlike chronic failure, AKI is often reversible with timely treatment, including rehydration, stopping offending drugs, or temporary dialysis. Symptoms, if present, may include:
- Sudden decrease in urine output
- Swelling (edema) especially of the legs and ankles
- Fatigue and confusion
Chronic Renal (Kidney) Failure (Chronic Kidney Disease, CKD)
Chronic kidney failure develops gradually, most commonly from chronic diseases that damage the kidneys over many years. Leading causes are:
- Diabetes (high blood sugar damages filtering units)
- High blood pressure (harms blood vessels in the kidneys)
- Long-term kidney inflammation (glomerulonephritis, lupus nephritis)
- Inherited conditions (e.g., polycystic kidney disease)
- Repeated urinary tract obstructions (enlarged prostate, stones)
Chronic kidney disease can progress unnoticed for a long time. Symptoms often emerge only in advanced stages or when complete failure occurs. When the function drops below a critical threshold, dialysis or kidney transplantation is required to sustain life.
How Is Kidney Failure Diagnosed?
No single test alone diagnoses kidney failure. Physicians consider your medical history, conduct a physical exam, and recommend a series of blood and urine tests to evaluate kidney function.
- Blood urea nitrogen (BUN) and creatinine: These increase as kidney function declines.
- Estimated Glomerular Filtration Rate (eGFR): A calculation based on creatinine level, age, gender, and ethnicity—indicates overall kidney function.
- Urine analysis: Looks for blood, protein, and other abnormalities.
- Imaging exams: Ultrasounds, CT scans may assess kidney size, structure, and detect obstructions.
Symptoms: What to Watch For
The signs of kidney failure depend on how quickly the problem develops, how much kidney function is lost, and whether it is acute or chronic. In the early stages, symptoms may be subtle or nonexistent.
- Decreased urine output, or sometimes increased urine output
- Swelling in legs, ankles, and around eyes
- Fatigue, weakness, or confusion
- Nausea and vomiting
- Shortness of breath
- Loss of appetite
- High blood pressure (due to fluid overload)
It is possible to experience none of these symptoms until kidney function is severely impaired. This makes regular screening important for people with risk factors.
Common Causes of Renal/Kidney Failure
- Acute (Sudden) Causes:
- Shock from blood loss, overwhelming infection, or trauma
- Serious dehydration
- Obstructions such as kidney stones or enlarged prostate
- Certain medications, toxins, or contrast agents
- Acute inflammation within the kidney (glomerulonephritis)
- Chronic (Long-term) Causes:
- Uncontrolled diabetes
- Poorly managed high blood pressure
- Inherited kidney diseases (e.g., polycystic kidney disease)
- Repeated kidney infections
- Chronic obstruction of urinary tract
Treatment Options for Kidney (Renal) Failure
Treatment depends on the type, stage, and cause of kidney failure. Major approaches include:
- Acute renal (kidney) failure:
- Treating underlying cause (e.g., stopping harmful drugs, restoring blood flow)
- Careful management of fluids and electrolytes
- Temporary dialysis in severe cases until kidneys recover
- Chronic kidney (renal) failure:
- Controlling blood pressure and diabetes
- Dietary modifications: Lowering salt, potassium, and fluid intake
- Medications to decrease proteinuria and support kidney function
- Dialysis or kidney transplant for end-stage disease
Prognosis and Outlook
Outcomes vary based on the underlying cause, how quickly diagnosis and treatment occur, and whether the failure is acute or chronic. Some key points:
- Acute kidney failure can often be reversed, especially if caught early.
- Chronic kidney failure is usually not reversible but can be slowed with proper management.
- At the end-stage, both require some form of kidney replacement therapy for survival.
Frequently Asked Questions (FAQs) About Renal and Kidney Failure
Q: Is there a difference between renal failure and kidney failure?
A: No. Both terms describe the inability of the kidneys to adequately filter waste products and maintain bodily fluid and electrolyte balance. Medical professionals use the terms interchangeably.
Q: What about ‘kidney disease’—is it the same as kidney failure?
A: Kidney disease is broader; it refers to any decline in kidney function, whereas kidney/renal failure means severely reduced function (end-stage disease) where medical intervention is required.
Q: Can kidney failure be reversed?
A: Acute kidney failure (AKI) is reversible in many cases with prompt and appropriate treatment. Chronic kidney failure generally cannot be reversed, but its progression may be slowed.
Q: What are the most common causes of kidney failure?
A: Diabetes and high blood pressure are the leading causes of chronic kidney failure. Acute failure is often due to sudden loss of blood flow, toxins, severe infection, or obstruction.
Q: What are the main treatments for kidney failure?
A: For acute causes, treating the underlying condition, managing fluid and electrolytes, and sometimes short-term dialysis. In chronic and end-stage cases, dialysis or kidney transplantation are necessary to replace lost kidney function.
Key Takeaways
- ‘Renal failure’ and ‘kidney failure’ are different names for the same condition.
- The main difference between ‘kidney disease’ and ‘kidney failure’ is the degree of kidney dysfunction—failure is the severe end.
- Causes, symptoms, and treatment options vary depending on whether the failure is acute or chronic.
- Early diagnosis and management can significantly affect the outcome, especially for acute kidney failure.
- If you have risk factors, routine medical checkups can help catch kidney problems early and preserve kidney health.
References
- https://www.medicalnewstoday.com/articles/acute-renal-failure-vs-acute-kidney-injury
- https://www.medicalnewstoday.com/articles/is-renal-failure-the-same-as-kidney-failure
- https://www.healthline.com/health/kidney-health/is-renal-failure-the-same-as-kidney-failure
- https://www.chop.edu/conditions-diseases/renal-failure-children
- https://www.youtube.com/watch?v=Wals-zEKHS4
- https://www.healthdirect.gov.au/kidney-failure
- https://www.kidneyfund.org/all-about-kidneys/stages-kidney-disease
- https://www.kidney.org/kidney-topics/kidney-failure
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