Kidney Disease in Aging: Causes, Symptoms, and Treatment

Have you been told that you — or an older person you care about — has kidney disease?

If so, you’re not alone: kidney disease is very common in older adults. Almost everyone’s kidney function declines at least a little with aging, with actual chronic kidney disease affecting an estimated 35% of people over age 65.

It’s also fairly common for older adults to develop an “acute kidney injury,” which means the kidneys suddenly start working less well. This often happens during an illness, dehydration, infection, or hospitalization.

Fortunately, in most cases, acute kidney injuries improve, and chronic kidney disease remains fairly manageable, with only a minority of older adults progressing to needing dialysis.

But kidney disease is still important to recognize and monitor, because it can affect medication safety, blood pressure, fluid balance, and overall health.

In this article, I’ll cover what older adults and families should know about kidney disease in aging.

Most people are born with two kidneys, located in the back of the body, just below the rib cage. Their main job is to continuously filter the blood and produce urine.

But the kidneys do much more than make urine. They are involved in many important body functions, including:

• Regulating fluid levels in the body
• Helping control blood pressure
• Keeping electrolytes such as sodium, potassium, calcium, chloride, and magnesium in balance
• Regulating the acidity, or pH, of the blood
• Removing waste products from the bloodstream
• Helping stimulate red blood cell production through a hormone called erythropoietin
• Helping convert vitamin D into its active form
• Helping metabolize and excrete certain medications

Each kidney contains millions of tiny filtering units called nephrons. Each nephron includes a glomerulus, which starts the filtering process, and a tubule, which reabsorbs needed substances and helps remove waste.

Normally, healthy kidneys keep important things like blood cells, large proteins, and glucose in the body. That’s why, under normal circumstances, those substances should not be found in significant amounts in the urine.

Kidney function is usually checked with blood tests that are part of a basic metabolic panel.

One of the most important numbers is the eGFR, or estimated glomerular filtration rate. This estimates how well the kidneys are filtering the blood.

A normal adult filtration rate is usually around 90 to 120 mL/min. This reflects the function of both kidneys together.

Other common kidney-related blood test results include:

• Creatinine: This is a waste product that tends to rise when kidney function declines. A typical normal range is about 0.7 – 1.3 mg/dL, although this varies by lab and by the person’s muscle mass.
• BUN, or blood urea nitrogen: This is another waste-related marker. A typical normal range is about 6 – 20 mg/dL.

It’s important to know that creatinine is affected by muscle mass. For instance, a petite older woman with low muscle mass may normally have a creatinine of 0.6. If it rises to 1.1, that may represent a meaningful decline in kidney function, even though 1.1 might look “normal” on many lab reports. (This is why it’s always useful to look at past lab results!)

If kidney dysfunction becomes more significant, other abnormalities may appear, such as high potassium levels or excess acidity in the blood.

There are three main kidney issues that commonly arise in medical care.

Chronic kidney disease

Chronic kidney disease (CKD) means there is long-term, ongoing evidence of kidney damage or reduced kidney function.

CKD is usually defined as either:

• Evidence of kidney damage, such as albumin or protein in the urine, or
• A filtration rate (eGFR) below 60 mL/min for at least three months

Chronic kidney disease is often caused by long-term damage from conditions such as high blood pressure or diabetes.

Acute kidney injury

Acute kidney injury means kidney function suddenly worsens over hours or days.

This can happen because of:

• Dehydration
• Low blood pressure
• Blood loss
• Infection
• Certain medications
• Urine blockage, such as from urinary retention or an enlarged prostate

Acute kidney injury is often reversible if the underlying problem is found and corrected.

Acute on chronic kidney disease

Sometimes an older adult already has chronic kidney disease and then develops an acute kidney injury on top of it. This is called acute-on-chronic kidney disease.

For example, someone may have mild chronic kidney disease for years, then become dehydrated during an illness and have their kidney function suddenly worsen.

One important thing to know is that mild to moderate kidney dysfunction usually causes no symptoms.

Many older adults with chronic kidney disease feel completely normal. Their kidney disease may only be noticed because of routine blood tests.

Even a GFR in the 50s often causes no symptoms. Kidney function can sometimes get significantly lower before a person feels unwell.

However, more severe kidney dysfunction can cause symptoms and complications, including:

• Fluid overload, such as significant leg swelling
• Worsening heart failure symptoms
• High potassium levels, which can cause muscle weakness, cramps, spasms, or irregular heart rhythms
• Uremia, which means waste products are building up in the blood

Significant uremia tends to cause symptoms. Symptoms of uremia can include:

• Confusion
• Drowsiness
• Itching
• Nausea
• Loss of appetite
• Vomiting

In older adults, new or worsening confusion is especially important to evaluate. This is often called delirium, and kidney dysfunction can be one possible cause or contributor.

Chronic kidney disease is often described in stages based on eGFR.

The general kidney function stages are:

It’s important to understand that most older adults with chronic kidney disease do not progress to stage 5 kidney failure, which may require dialysis to control fluids and electrolytes.

Many people remain in the mild or moderate stages for a long time. In these cases, the main focus is usually monitoring kidney function, protecting the kidneys, avoiding medication-related harm, and managing contributing conditions.

The most common causes of chronic kidney disease in older adults are long-term damage from:

• High blood pressure
• High blood sugar, especially diabetes

These conditions can gradually damage the small blood vessels and filtering structures in the kidneys.

Other causes or contributors include:

• Chronic use of medications that can stress the kidneys, such as NSAIDs
• Kidney infections or other serious infections
• Autoimmune diseases
• Blocked urine flow
• Kidney stones
• Tumors
• Enlarged prostate causing urinary retention
• Smoking
• Obesity
• Other conditions that increase inflammation

Aging itself is also associated with a gradual decrease in kidney function. One estimate is that GFR declines by about 1% per year with age, or about 8 mL/min per decade starting in midlife.

This doesn’t mean kidney disease should be ignored or dismissed as “just aging.” But it does mean that some decline in kidney filtration is common in later life.

Because chronic kidney disease (CKD) often causes no symptoms, it may not seem urgent. But it’s still important to know about it.

If you have CKD, you and your health providers may need to take steps to:

• Avoid or minimize medications that can worsen kidney function
• Adjust doses of certain medications
• Monitor kidney function over time
• Control blood pressure
• Manage diabetes or high blood sugar
• Check for protein or albumin in the urine
• Reduce the risk of progression
• Watch for complications such as electrolyte problems or anemia

One common medication group to be careful with is NSAIDs, or non-steroidal anti-inflammatory drugs. These include medications such as ibuprofen and naproxen.

NSAIDs can be useful in some situations, but they can stress the kidneys, especially in older adults who already have CKD, dehydration, heart failure, or are taking certain blood pressure medications.

Kidney dysfunction is often first noticed on routine bloodwork, especially a basic metabolic panel.

If kidney function looks abnormal, the next steps depend on several factors:

• How low the eGFR is
• Whether creatinine and BUN are elevated
• Whether the change appears sudden or gradual
• Whether the person is currently ill
• Whether there are symptoms such as dehydration, infection, low blood pressure, or urinary problems
• The person’s past medical history
• Current medications

Health providers usually try to determine:

• What stage of kidney disease is present
• Whether the problem looks acute, chronic, or acute-on-chronic
• Whether there is albumin or protein in the urine
• What is the likely underlying cause
• Whether the cause can be treated or better managed

A medication review is especially important. Sometimes a medication is contributing to the kidney problem, or a medication dose may need to be adjusted because kidney function has declined.

Hydration status also matters, especially in frail older adults or those who have recently been ill.

In some cases, the best next step may simply be to repeat the blood test in one to two weeks, especially if the abnormality is mild or if dehydration or illness may have been involved.

Additional tests may include:

• A more detailed urinalysis
• Urine testing for albumin or protein
• Microscopic examination of the urine
• Kidney ultrasound
• Other specialized blood or urine tests, depending on the situation

Kidney specialists are called nephrologists.

Much of the evaluation and management of mild-to-moderate chronic kidney disease can be handled in primary care. But a nephrology referral may be especially important if:

• eGFR is less than 30 mL/min
• Kidney function is declining quickly
• There is a very high level of protein in the urine
• There is blood in the urine that appears to come from the kidney’s filtering structures
• The diagnosis is unclear
• Advanced kidney disease is approaching and dialysis or transplant planning may need to be discussed

A primary care clinician can help determine when a nephrology referral is appropriate.

The main goals of chronic kidney disease management are to protect remaining kidney function, reduce progression, and prevent complications.

Common management steps include:

1. Control blood pressure

High blood pressure can damage the kidneys over time. Blood pressure control is one of the most important parts of protecting kidney function. (See below for more on which BP medications are especially good for the kidneys.)

2. Avoid medications that stress the kidneys

NSAIDs such as ibuprofen and naproxen can worsen kidney function in some people, especially when used regularly or during dehydration or illness.

Other medications may also need caution or dose adjustment, depending on kidney function.

3. Treat the underlying cause when possible

If diabetes, high blood pressure, urinary obstruction, infection, or another condition is contributing, managing that condition is key.

4. Manage blood sugar

High blood sugar can damage the kidneys over time. For people with diabetes, glucose management is an important part of kidney protection.

5. Check for albumin in the urine

Albumin in the urine can be a sign of kidney damage. It also helps health providers estimate the risk of kidney disease progression and decide which treatments may be helpful.

6. Consider kidney-protective medications when appropriate

For people with CKD and albuminuria, certain medications have been shown to slow progression in many cases.

These may include:

• ACE inhibitors
• Angiotensin receptor blockers, also called ARBs
• SGLT2 inhibitors

ACE inhibitors and ARBs are commonly used for blood pressure control. SGLT2 inhibitors were originally developed for diabetes, but they have also been found to have kidney-protective effects in certain people with chronic kidney disease.

As always, whether these medications are appropriate depends on the person’s overall health, lab results, blood pressure, medication list, and goals of care.

Kidney failure generally refers to very advanced kidney dysfunction, often when eGFR is around 15 mL/min or lower.

At that stage, the kidneys may no longer be able to adequately remove fluid, waste products, and excess electrolytes from the body. Severe kidney failure can eventually lead to death unless kidney function is replaced or managed in another way.

The main treatment options for end-stage kidney disease include:

• Dialysis
• Kidney transplant
• Conservative kidney management

What Is Dialysis?

Dialysis is a medical treatment that filters the blood to remove excess fluid and waste products.

There are two main forms:

• Hemodialysis: Blood is filtered through a machine. This is the most common form used in the United States.
• Peritoneal dialysis: The lining of the abdominal cavity is used to help filter waste and fluid.

Dialysis can be used temporarily in the hospital for severe acute kidney injury. It can also be used long-term for advanced chronic kidney disease.

Most people with chronic kidney disease do not progress to needing dialysis. But for those who do, planning often starts when eGFR is around 20 – 25 mL/min.

This early planning matters because long-term dialysis usually requires special preparation, such as creating a vascular access point for hemodialysis.

Kidney Transplant in Older Adults

Kidney transplant can be an option for some older adults with end-stage kidney disease, especially if they are otherwise in reasonably good health.

However, transplant is a major procedure and requires significant ongoing medical care afterward, including medications to prevent rejection.

Whether transplant is a realistic option depends on the person’s overall health, frailty, other medical conditions, and preferences.

Conservative Kidney Management

Another option for advanced kidney disease is conservative kidney management, which is a palliative approach.

This means focusing on comfort, symptom management, and quality of life rather than dialysis or transplant.

This option can be especially worth considering when someone is much older, frail, has advanced dementia, or has multiple serious medical conditions.

Dialysis can be burdensome. It often involves frequent appointments, procedures, dietary restrictions, and medical complications. For some older adults, especially those with significant frailty or limited life expectancy, dialysis may not improve quality of life in a meaningful way.

A conservative approach does not mean “doing nothing.” It means actively managing symptoms and supporting the person in a way that fits their health situation and goals.

In geriatrics, kidney disease is very common, and it often interacts with other health problems.

Here are a few important points for older adults and families:

• Many older adults have mild-to-moderate CKD and no symptoms.
• Kidney function should be checked if an older person develops new or worsening confusion.
• Acute kidney injury can happen during dehydration, infection, urinary obstruction, or hospitalization.
• Medication safety becomes especially important when kidney function declines.
• Dialysis and transplant can be options for some older adults.
• Conservative kidney management should also be discussed when advanced kidney disease occurs in someone who is frail or has serious other conditions.

The best approach depends not only on the kidney function numbers, but also on the person’s overall health, function, preferences, and goals.

If you or your older relative has abnormal kidney test results, consider asking:

• Can I have a copy of my lab results?
• What is my eGFR?
• Is the abnormal result mild, moderate, or severe?
• How does this compare to my prior kidney test results?
• Does this look like chronic kidney disease, acute kidney injury, or acute-on-chronic kidney disease?
• Do I have albumin or protein in my urine?
• What do you think is the most likely cause?
• Could any of my medications be affecting my kidneys?
• Do any of my medication doses need to be adjusted?
• Should I avoid NSAIDs such as ibuprofen or naproxen?
• What is the plan for further evaluation?
• What is the plan for managing or protecting my kidney function?
• How often should my kidney function be monitored?
• Should I see a nephrologist?

It’s also a good idea to keep copies of lab results and track kidney function over time. This can help you and your health providers notice important changes sooner.

Kidney disease is common in older adults, and it often causes no symptoms in the early or moderate stages.

The key number to know is usually the eGFR, which estimates how well the kidneys are filtering the blood. Chronic kidney disease is often defined as an eGFR below 60 mL/min for at least three months, or evidence of kidney damage such as albumin in the urine.

The most common causes of chronic kidney disease are high blood pressure and diabetes. Other contributors can include certain medications, infections, blocked urine flow, autoimmune disease, smoking, obesity, and age-related decline.

For most older adults with CKD, treatment focuses on monitoring kidney function, controlling blood pressure and blood sugar, avoiding kidney-stressing medications, adjusting medication doses when needed, and slowing progression.

And for those who develop advanced kidney disease, it’s important to understand all the options, including dialysis, transplant, and conservative kidney management.

I hope this article has helped you better understand any kidney disease affecting your life or that of someone you care about.