Your kidneys work around the clock, filtering waste, balancing fluids, and helping control blood pressure. But when they begin to lose function, the warning signs can be surprisingly subtle.
Swollen ankles, puffy eyes, unusual fatigue, or changes in your urine might seem like ordinary problems associated with aging. Yet sometimes, these symptoms can indicate that your kidneys are no longer working as efficiently as they should.
According to the Centers for Disease Control and Prevention (CDC), more than 1 in 7 American adults are estimated to have chronic kidney disease (CKD), and many don’t know they have it.
One of the most concerning things about kidney disease is that it can progress for years without noticeable symptoms.
Recognizing potential warning signs is important, but symptoms alone cannot diagnose kidney disease. Blood and urine tests are essential.
Here are seven signs worth paying attention to.
1. Swollen Feet, Ankles, or Legs
Have you noticed that your shoes feel tighter than usual or that your ankles appear swollen at the end of the day?
When the kidneys cannot remove excess sodium and fluid effectively, fluid may accumulate in the body.
This condition, called edema, can cause swelling in the feet, ankles, legs, and sometimes the hands.
You might notice:
- Socks leaving unusually deep marks around your ankles.
- Shoes feeling tighter than normal.
- Swelling that becomes more noticeable during the day.
- Skin that briefly retains an indentation after being pressed.
However, swelling does not automatically mean kidney disease.
Heart failure, liver disease, vein problems, certain medications, and prolonged sitting can also cause edema.
Persistent or unexplained swelling deserves medical evaluation, especially if you have diabetes, high blood pressure, or a history of kidney problems.
2. Puffy Eyes, Especially in the Morning
Waking up with swollen or puffy eyelids is common and often harmless.
Allergies, poor sleep, crying, and temporary fluid retention can cause this appearance.
However, persistent puffiness around the eyes can sometimes be associated with kidney problems.
One possible explanation is protein leaking into the urine.
Healthy kidneys normally keep most proteins, including albumin, in the bloodstream.
When the kidney’s filtering structures become damaged, albumin may escape into the urine, a condition known as albuminuria.
In certain kidney disorders, substantial protein loss can contribute to fluid accumulation around the eyes and elsewhere.
If puffiness is persistent, especially alongside leg swelling or foamy urine, a healthcare professional may recommend urine and blood tests.
3. Changes in Urination
Changes in your urinary habits can sometimes provide clues about kidney or urinary tract health.
Some people with kidney disease notice that they need to urinate more frequently, particularly at night.
Others may experience changes in urine volume, although significant reductions in urine output are more concerning for certain acute or advanced conditions.
Possible changes include:
- Urinating more often than usual, especially at night.
- Urine that appears unusually foamy.
- Blood or reddish discoloration in the urine.
- A significant change in the amount of urine produced.
What does foamy urine mean?
Occasional bubbles in the toilet are not necessarily a problem.
A strong urine stream or concentrated urine can produce temporary foam.
However, persistent, unusually foamy urine may indicate protein in the urine, which should be checked.
A urine albumin-to-creatinine ratio (uACR) test can help detect abnormal protein leakage.
What about blood in the urine?
Blood in the urine may be caused by infections, kidney stones, kidney disease, or urinary tract cancers.
Visible blood in the urine should always be evaluated by a healthcare professional, even if it occurs only once.
4. Unusual Fatigue, Weakness, or Difficulty Concentrating
Everyone feels tired occasionally.
But persistent exhaustion that doesn’t improve with adequate rest can sometimes be associated with reduced kidney function.
The kidneys perform several important functions beyond filtering waste.
They also produce erythropoietin, a hormone that stimulates the production of red blood cells.
When kidney function declines, erythropoietin production may decrease, contributing to anemia.
Anemia reduces the blood’s ability to carry oxygen efficiently throughout the body.
Symptoms may include unusual tiredness, weakness, dizziness, shortness of breath during activity, and difficulty concentrating.
Advanced kidney dysfunction can also lead to the accumulation of substances normally removed from the bloodstream, contributing to fatigue and cognitive symptoms.
These problems are not unique to kidney disease. Thyroid disorders, iron deficiency, sleep disorders, and many other conditions can cause similar symptoms.
Persistent unexplained fatigue deserves medical assessment.
5. Persistent Itchy or Unusually Dry Skin
Dry skin is extremely common, especially during colder months and as people get older.
However, persistent itching can sometimes be associated with advanced chronic kidney disease.
This condition is often called chronic kidney disease-associated pruritus.
The exact causes are complex and may involve changes in nerve signaling, inflammation, and other processes associated with reduced kidney function.
Some people experience widespread itching without a visible rash.
Others notice that the itching interferes with sleep or daily activities.
Dry skin and itching can also result from eczema, allergies, medication reactions, liver disease, and other medical conditions.
Itching alone is not a reliable early warning sign of kidney disease.
However, persistent itching alongside other symptoms or known kidney problems should be discussed with a healthcare professional.
6. Loss of Appetite, Nausea, or a Metallic Taste
As kidney disease becomes more advanced, waste products that are normally filtered from the blood may accumulate.
This can contribute to symptoms such as reduced appetite, nausea, vomiting, and changes in taste.
Some people describe an unpleasant or metallic taste in their mouth.
Others notice that foods they previously enjoyed no longer seem appealing.
Unintentional weight loss may occur when appetite remains poor over time.
These symptoms are more commonly associated with advanced kidney dysfunction than early-stage disease.
They can also occur with digestive conditions, medication side effects, infections, and many other health problems.
Persistent nausea, vomiting, or unexplained weight loss should be medically evaluated.
7. Shortness of Breath or Trouble Sleeping
Difficulty breathing can sometimes occur when advanced kidney disease causes excess fluid to accumulate in the body.
In some cases, fluid can build up in the lungs, making breathing difficult.
Kidney-related anemia may also contribute to breathlessness during physical activity.
People with kidney disease can experience sleep disturbances for several reasons, including itching, restless legs, sleep apnea, and other associated health conditions.
However, shortness of breath has many potential causes, including heart and lung disease.
Sudden or severe shortness of breath is a medical emergency.
Call 911 in the United States or your local emergency number if breathing becomes severely difficult, especially when accompanied by chest pain, confusion, or fainting.
Why Kidney Disease Can Develop Without Obvious Symptoms
One of the most important things to understand about chronic kidney disease is that early stages frequently produce no noticeable symptoms.
The kidneys have considerable functional reserve.
A person may lose some kidney function without experiencing pain or obvious changes in daily life.
This is why kidney disease is often discovered through routine blood or urine testing.
Chronic kidney disease generally refers to abnormalities of kidney structure or function that persist for at least three months and have implications for health.
Doctors assess kidney function using measurements such as estimated glomerular filtration rate (eGFR) and urine albumin levels.
An abnormal test result does not always mean someone has chronic kidney disease. The result must be interpreted in context, and repeat testing may be necessary.
Who Is Most at Risk of Kidney Disease?
Certain medical conditions significantly increase the likelihood of developing chronic kidney disease.
| Risk factor | Why it matters |
|---|---|
| Diabetes | High blood sugar can damage the kidneys’ filtering structures |
| High blood pressure | Can damage small blood vessels in the kidneys |
| Heart disease | Shares several risk factors with kidney disease |
| Family history | Some kidney disorders have inherited components |
| Older age | Kidney disease becomes more common with age |
| Obesity | Increases the risk of diabetes, hypertension, and kidney damage |
| Previous kidney injury | May increase the risk of later chronic kidney problems |
Diabetes and high blood pressure are two of the leading causes of chronic kidney disease in the United States.
People with these conditions should discuss appropriate kidney testing with their healthcare professionals, even when they feel completely healthy.
The Two Important Tests That Can Reveal Kidney Problems
Doctors commonly use two types of tests to assess kidney health.
1. Blood test: eGFR
The estimated glomerular filtration rate measures how efficiently the kidneys filter blood.
It is usually calculated using a blood creatinine measurement along with other relevant factors.
A lower eGFR may indicate reduced kidney function.
An eGFR below 60 mL/min/1.73 m² that persists for at least three months can meet one criterion for chronic kidney disease.
However, a single abnormal result requires medical interpretation and may need to be repeated.
2. Urine test: uACR
The urine albumin-to-creatinine ratio measures how much albumin is leaking into the urine.
Albumin is a protein that healthy kidneys generally retain in the bloodstream.
A uACR of 30 mg/g or higher is considered elevated.
Persistent albuminuria may indicate kidney damage even when the eGFR remains relatively normal.
These tests provide complementary information, which is why both are valuable.
Can Kidney Disease Be Treated?
Yes. Although some kidney damage cannot be reversed, treatment can often slow progression and reduce the risk of serious complications.
Treatment depends on the underlying cause, kidney function, urine albumin levels, and the patient’s overall health.
Control blood pressure
Managing high blood pressure is one of the most important ways to protect kidney function.
Certain blood-pressure medications, including ACE inhibitors and angiotensin receptor blockers, can provide additional kidney protection in appropriate patients.
Manage diabetes
For people with diabetes, maintaining appropriate blood glucose levels can reduce the risk of kidney complications.
Some medications, including SGLT2 inhibitors, have demonstrated kidney-protective benefits in eligible patients with chronic kidney disease, including some people without diabetes.
Reduce excess sodium
Eating too much sodium can contribute to high blood pressure and fluid retention.
A healthcare professional or registered dietitian can recommend an appropriate dietary plan.
Avoid unnecessary kidney stress
Certain medications, particularly nonsteroidal anti-inflammatory drugs such as ibuprofen and naproxen, can worsen kidney function in susceptible individuals.
People with kidney disease should discuss over-the-counter pain medications and supplements with their healthcare team.
Do not stop prescribed medications without medical guidance.
Treat advanced disease appropriately
For people with severe kidney failure, treatment may eventually involve dialysis or kidney transplantation.
However, many people with chronic kidney disease never require these treatments, particularly when the condition is identified and managed early.
How to Help Protect Your Kidneys After Age 50
Protecting kidney health involves many of the same habits that support cardiovascular health.
Maintaining healthy blood pressure and blood sugar levels is especially important.
Other helpful habits include regular physical activity, avoiding smoking, eating a balanced diet, maintaining a healthy weight, and following medical advice about medications.
Adequate hydration matters, but drinking excessive amounts of water does not cleanse damaged kidneys or cure kidney disease.
People with advanced kidney disease or heart failure may need individualized fluid recommendations.
There is no universal amount of water that is appropriate for everyone.
When Should You Seek Immediate Medical Help?
Some symptoms may indicate a serious kidney or cardiovascular emergency.
Seek emergency medical care if you experience:
- Severe difficulty breathing.
- Very little or no urine output accompanied by significant illness.
- Sudden confusion, collapse, or loss of consciousness.
- Severe weakness with chest pain or dangerous heart rhythm symptoms.
- Severe flank pain with fever or signs of serious infection.
Visible blood in the urine, persistent swelling, and significant changes in urination also require prompt medical evaluation, even when emergency symptoms are absent.
The Bottom Line: Don’t Wait for Symptoms to Check Your Kidneys
Kidney disease is often called a silent condition because it can develop gradually without obvious warning signs.
Swollen ankles, persistent puffiness around the eyes, foamy urine, unusual fatigue, itching, nausea, and breathlessness can sometimes occur when kidney function is impaired.
But these symptoms are not specific to kidney disease, and many people with early kidney damage feel completely normal.
If you’re over 50, especially if you have diabetes or high blood pressure, ask your healthcare provider whether you should have your kidney function and urine albumin checked.
Early detection and appropriate treatment can help protect kidney function and reduce the risk of complications.
Medical disclaimer: This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. If you experience severe breathing difficulty, confusion, or other emergency symptoms, seek immediate medical assistance.
Trusted medical references
- CDC — Chronic Kidney Disease
- National Institute of Diabetes and Digestive and Kidney Diseases — Chronic Kidney Disease
- National Kidney Foundation — Chronic Kidney Disease
- KDIGO — Clinical Practice Guideline for the Evaluation and Management of CKD
