“Renal insufficiency” is a broad term for all stages of kidney impairment, including renal failure. “Renal failure,” however, can refer to a specific level of kidney decline.
Feeling tired, experiencing muscle cramps, and noticing changes in urination — particularly at night — can all be subtle signs of declining kidney function.
While renal insufficiency may be mild or reversible, full renal failure usually requires renal replacement therapy.
This article examines renal insufficiency and renal failure, their differences and similarities, and more.
People often use the terms “renal insufficiency,” “kidney disease,” and “renal failure” interchangeably to describe when renal system function drops below healthy levels.
Under these umbrella terms, there are various classifications for declining renal function.
Acute kidney injury, which doctors also refer to as acute renal failure (ARF), is an abrupt form of renal insufficiency where kidney function declines sharply over a short period. This condition is usually reversible.
Chronic renal failure (CRF), also called chronic kidney disease (CKD), is when renal insufficiency becomes persistent and progressive. CRF is present over a longer period, and there is currently no cure.
If kidney function drops below
ARF typically occurs abruptly over a few hours or days.
Under diagnostic guidelines put forth by the Kidney Disease: Improving Global Outcomes organization, ARF
- a creatinine increase of 0.3 milligrams per deciliter in 48 hours
- a creatinine increase to 1.5 times baseline within the last 7 days
- urine volume of fewer than 0.5 milliliters (mL) per kilogram per hour for 6 hours
Experts define CRF as a gradual decline of renal function over time. It can be a progressive condition that eventually evolves into ESRD.
A doctor
What is GFR?
At the start of urine production, blood components pass through a bundle of capillaries that make up the kidney’s glomerulus, or filtering unit. Pressure causes fluid to move through several layers that create selective filtration between water and solutes in a process called glomerular filtration. GFR is the rate at which this filtration occurs.
Typical GFR is
Doctors classify CRF into stages based on GFR levels.
The following table shows information from the American Kidney Fund on the stages of renal failure.
| Stage | GFR level (mL/min) | Effects |
|---|---|---|
| 1 | 90 or more | Although the kidneys function normally, urine tests suggest kidney disease. There may be mild kidney damage. |
| 2 | 60–89 | While there may be mild kidney damage, the kidneys still work well. |
| 3a | 45–59 | There may be mild to moderate kidney damage, and the kidneys do not work as well as they should. |
| 3b | 30–44 | There may be moderate to severe kidney damage, and the kidneys do not work as well as they should. |
| 4 | 15–29 | There is severe kidney damage, and the kidneys have almost stopped working. |
| 5 (ESRD) | below 15 | There is very severe kidney damage, and the kidneys have stopped or almost stopped working. |
The symptoms of renal failure can vary depending on the severity of renal insufficiency. In mild cases, a person may not notice any warning signs.
Symptoms of renal failure include:
- low urine output
- itchy, dry skin
- muscle cramps
- weakness or numbness
- painful joints
- nausea
- appetite changes
- fatigue
- swelling in the legs, ankles, or feet
Treatment for renal insufficiency can involve medication or diet and lifestyle changes. In ESRD, a person may require renal replacement therapy in the form of dialysis or a kidney transplant.
- Medications: Medications for renal failure primarily address underlying causes such as diabetes, high cholesterol, or high blood pressure. They may include ACE inhibitors, angiotensin receptor blockers, or blood pressure medications.
- Diet: Dietary changes, such as managing salt and sodium intake, may be necessary to manage CKD. Other
common dietary changes include monitoring protein intake and limiting saturated and trans fats. - Lifestyle changes: Certain lifestyle changes may help people manage CKD, including stopping smoking if the person smokes, avoiding alcohol, and exercising regularly.
This section answers some commonly asked questions about renal insufficiency and renal failure.
Are there medications to avoid when living with renal failure?
Yes, experts generally recommend those with reduced kidney function avoid nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen. This is because they can harm the kidneys.
Additionally, because aspirin can increase the risk of bleeding, anyone with reduced kidney health should consult a doctor before taking it.
A person with kidney problems should talk with a doctor before taking any OTC pain medications.
Will CKD cause anemia?
Some people who develop renal insufficiency
Anemia in CKD occurs when damaged kidneys produce less of the hormone required to stimulate red blood cell production.
How often will I need dialysis?
Dialysis frequency depends on the functional level of the kidneys. In general, dialysis occurs several times a week, lasting up to 4 hours per session.
Is renal insufficiency a part of natural aging?
It is natural for kidney function to change as you age.
According to the National Kidney Foundation, people over the age of 60 are more likely to develop kidney disease. However, not everyone will experience problematic kidney function as they age.
Will kidney failure impact my sex life?
Kidney failure
How do doctors diagnose renal insufficiency?
A doctor will conduct a physical examination and review a person’s medical history before diagnosing renal insufficiency.
In addition to a standard vitals assessment, the physical examination may include checks for abdominal discomfort, skin condition changes, and signs of fluid retention.
Laboratory and diagnostic imaging tests may include:
- urinalysis
- blood work
- renal ultrasound
- abdominal X-ray
- cystoscopy, which involves inserting a tool into the urethra and bladder
- kidney biopsy
- MRI or CT scans
What is the difference between kidney disease and CKD?
“Kidney disease” is a synonym for renal failure in many situations. It is an encompassing term suggesting changes in the kidneys’ ability to function properly.
People can also use it to describe short- or long-term kidney conditions.
Chronic kidney disease commonly describes the progressive loss of kidney function. However, it can also describe specific chronic conditions affecting kidney health, such as polycystic kidney disease.
Renal insufficiency and renal failure often describe the same declines in kidney functionality, though renal failure may indicate a specific point when kidney function is almost nonexistent.
While chronic kidney disease is often progressive and irreversible, a person may be able to slow the condition’s process through lifestyle changes, dietary awareness, and the use of medications to manage other chronic health conditions.