Therefore, persistent swelling should be investigated rather than automatically blamed on the kidneys.

5. Puffiness Around the Eyes

Kidney-related fluid retention can sometimes appear around the eyes, particularly as puffiness.

This may be more noticeable in the morning.

One reason is that certain kidney disorders can cause protein—particularly albumin—to leak into the urine.

When blood albumin levels become significantly reduced, fluid can move more easily from blood vessels into surrounding tissues.

This can contribute to swelling.

But puffy eyes are extremely common and can result from lack of sleep, allergies, crying, sinus problems, dehydration, genetics, or other causes.

Persistent or unusual swelling, especially when accompanied by leg swelling or changes in urination, is more worth discussing with a doctor.

6. Unexplained Fatigue

Feeling tired is one of the most common symptoms in medicine.

Stress, insufficient sleep, anemia, infections, thyroid disorders, depression, nutritional deficiencies, and countless other conditions can cause fatigue.

Kidney disease is another possibility, particularly when kidney function becomes significantly reduced.

One reason is anemia.

Healthy kidneys produce a hormone called erythropoietin, which signals the bone marrow to produce red blood cells.

When kidney function declines substantially, the kidneys may produce less erythropoietin.

Anemia can develop, potentially contributing to:

• Fatigue

• Weakness

• Reduced exercise tolerance

• Shortness of breath

• Difficulty concentrating

Therefore, persistent unexplained fatigue can be worth evaluating—but it should never be assumed to indicate kidney disease without appropriate testing.

7. Trouble Concentrating or Feeling Mentally Foggy

Advanced kidney dysfunction can affect the nervous system.

When the kidneys are no longer able to adequately clear certain waste products from the blood, those substances can accumulate.

This can contribute to symptoms such as:

• Difficulty concentrating

• Reduced alertness

• Confusion

• Sleepiness

• Problems with memory or thinking

These symptoms are more concerning when kidney disease is already advanced.

Mild occasional forgetfulness, however, is not automatically a sign of kidney problems.

Stress, sleep deprivation, medications, anxiety, aging, and many other factors can affect concentration.

A significant or rapidly developing change in mental status should receive medical attention.

8. Dry or Itchy Skin

Persistent itching can occur in people with advanced chronic kidney disease.

The exact mechanisms are complex and may involve changes in mineral metabolism, inflammation, nerve signaling, and accumulation of substances normally removed by healthy kidneys.

Kidney-related itching can sometimes be widespread rather than limited to one particular area.

But itching is extremely nonspecific.

Dry skin, eczema, allergies, medications, liver disease, thyroid disorders, and many other conditions can cause it.

So persistent unexplained itching is a reason for evaluation—not proof of kidney disease.

9. Muscle Cramps or Twitching

Changes in kidney function can affect the body's balance of minerals and electrolytes.

The kidneys help regulate substances such as:

• Sodium

• Potassium

• Calcium

• Phosphate

When kidney function becomes significantly impaired, these systems can become disrupted.

Some people may experience muscle cramps, weakness, or other neuromuscular symptoms.

However, muscle cramps are also extremely common among healthy people.

They can be related to exercise, dehydration, medications, electrolyte abnormalities, circulation problems, or prolonged periods in one position.

Persistent or severe cramps should therefore be assessed in context.

10. Nausea or Loss of Appetite

As kidney disease becomes more advanced, waste products can accumulate in the bloodstream.

This may contribute to gastrointestinal symptoms such as:

• Nausea

• Reduced appetite

• An unpleasant taste in the mouth

• Changes in food preferences

• Unintentional weight loss