• Muscle cramps

• Twitching

• Weakness

• Restlessness in the legs

However, cramps are incredibly common.

They can occur after exercise, dehydration, prolonged standing, medication use, or changes in electrolyte levels unrelated to kidney disease.

Persistent or severe muscle symptoms should be evaluated rather than self-diagnosed.

13. Unusual Fatigue or Weakness

Fatigue can be one of the most frustrating symptoms because it has so many possible explanations.

In advanced chronic kidney disease, fatigue may occur because of anemia, buildup of waste products, sleep disturbances, inflammation, or other metabolic changes.

Someone might feel tired despite getting what seems like enough sleep.

They may have less energy for ordinary activities or find physical exertion more difficult.

Fatigue alone does not indicate kidney disease.

But persistent unexplained fatigue combined with changes in urination, swelling, itching, nausea, or high blood pressure warrants a conversation with a healthcare professional.

14. Nausea, Poor Appetite, or a Metallic Taste

When kidney function becomes severely impaired, waste products can accumulate in the bloodstream.

This can contribute to symptoms such as:

• Nausea

• Poor appetite

• An unpleasant or metallic taste

• Food tasting different

• Unintentional weight loss

These symptoms generally occur in more advanced illness rather than being reliable early warning signs.

They can also result from gastrointestinal conditions, medications, infections, dental problems, and many other causes.

Persistent nausea or unexplained appetite changes should therefore be investigated rather than automatically blamed on the kidneys.

15. Breathlessness

Severe kidney disease can sometimes contribute to shortness of breath.

There are several possible mechanisms.

Fluid accumulation can affect the lungs, while anemia can reduce the blood's oxygen-carrying capacity.

People with kidney disease may also have cardiovascular conditions that contribute to breathlessness.

But shortness of breath is a symptom that has many potentially serious causes.

Sudden or severe difficulty breathing requires urgent medical attention, particularly if it occurs with chest pain, confusion, fainting, or bluish lips.

16. Difficulty Concentrating or Feeling Mentally Foggy

In advanced kidney failure, significant accumulation of waste products can affect the nervous system.

A person may experience:

• Difficulty concentrating

• Sleepiness

• Confusion

• Problems thinking clearly

• Reduced alertness

These symptoms are not typical signs of mild kidney disease.

They are more concerning when kidney function is severely impaired.

Sudden confusion or a major change in mental status is an emergency and can have many causes unrelated to the kidneys.

17. High Blood Pressure That Becomes Difficult to Control

This isn't necessarily a visible sign, but it is one of the most important clues connected with kidney health.

The kidneys help regulate blood pressure through fluid balance and hormonal systems.

At the same time, high blood pressure can damage the kidneys.

This creates a potentially harmful cycle:

High blood pressure → kidney damage → worsening blood-pressure control → further kidney damage.

If blood pressure remains high despite treatment, healthcare professionals may investigate kidney function and other potential causes.

Because high blood pressure often produces no symptoms, regular measurement is important.

Why Kidney Disease Can Be Difficult to Detect

One of the biggest problems with kidney disease is that symptoms may not appear until kidney function has already declined significantly.

A person can feel completely healthy while laboratory testing reveals evidence of kidney damage.

This is particularly important for people with risk factors such as:

• Diabetes

• High blood pressure

• Cardiovascular disease

• Family history of kidney disease

• Previous kidney injury

• Certain autoimmune conditions

• Older age

• Long-term use of some medications

If you have significant risk factors, routine testing may detect kidney problems before obvious symptoms appear.

Two Simple Tests Can Provide Important Information

Doctors commonly assess kidney health using blood and urine tests.

A blood test can measure serum creatinine, which is used to estimate the estimated glomerular filtration rate (eGFR).

The eGFR provides an estimate of how effectively the kidneys are filtering blood.

A urine test can measure albumin, particularly through the urine albumin-to-creatinine ratio (UACR).

Together, these tests can provide important information about kidney function and kidney damage.

Blood pressure measurement is also an important part of kidney-health assessment.

Don't Wait for Symptoms to Protect Your Kidneys

Because early kidney disease may produce few symptoms, prevention and risk-factor management matter.

Helpful habits include:

Keep blood pressure under control

High blood pressure is one of the major causes and consequences of chronic kidney disease.

Follow your healthcare professional's treatment plan and monitor your blood pressure when recommended.

Manage blood glucose

Diabetes is a major risk factor for chronic kidney disease.

Keeping blood glucose within the range recommended by your healthcare team can help reduce complications.

Avoid unnecessary medication use

Some medications, particularly frequent or long-term use of certain nonsteroidal anti-inflammatory drugs (NSAIDs), can affect kidney function.

Don't stop a prescribed medication without discussing it with your clinician, but do ask whether over-the-counter medicines are appropriate for you.

Stay adequately hydrated

Normal hydration supports kidney function, but there is no need to force excessive amounts of water.

People with certain heart or kidney conditions may actually need fluid restrictions.

Follow individualized medical advice.

When Kidney-Related Symptoms Need Urgent Attention

Some symptoms should not wait for a routine appointment.

Seek urgent medical care if you experience very little or no urine, severe shortness of breath, severe weakness, confusion, fainting, significant blood in the urine, severe flank pain with fever, or rapidly worsening swelling or illness.

Sudden symptoms can have causes other than kidney disease, some of which also require immediate treatment.

The Bottom Line

Your kidneys perform essential work every minute, yet kidney problems can remain surprisingly quiet.

Changes such as persistent foamy urine, blood in the urine, swelling around the legs or eyes, unusual changes in urination, persistent itching, unexplained fatigue, or difficult-to-control blood pressure can sometimes provide clues that deserve investigation.

But these signs are not diagnoses.

Many have much more common explanations.

The most useful approach is to pay attention to changes that are new, persistent, or occurring in combination and to seek appropriate testing when necessary.

If you're at increased risk because of diabetes, high blood pressure, cardiovascular disease, family history, or another medical condition, don't wait until symptoms become obvious.

A simple blood test, urine test, and blood-pressure check can reveal important information about kidney health long before you feel seriously ill.

Your kidneys may not always give you a loud warning.

Sometimes, the earliest clue is simply a small change your body keeps repeating.

And recognizing that change—and getting it checked—is far more useful than trying to diagnose yourself from a single symptom.