Your kidneys work quietly in the background every day. These two small organs filter waste from the blood, help control fluid and electrolyte balance, contribute to blood-pressure regulation, and support the production of red blood cells.

The surprising part is that kidney disease can develop for years without obvious symptoms.

When symptoms finally appear, some may be visible changes that seem unrelated to the kidneys. Swelling around the eyes, swollen ankles, changes in the skin, altered urine, or unusual paleness can sometimes provide clues that deserve medical attention.

However, none of these signs proves that someone has kidney disease. Many have other possible explanations. The important thing is recognizing persistent or unusual changes and knowing when to get them evaluated.

Here are 17 signs and changes worth knowing about.

1. Swelling Around the Ankles and Feet

One of the more recognizable signs associated with reduced kidney function is fluid retention.

When the kidneys have difficulty maintaining the body's fluid and sodium balance, excess fluid can accumulate in tissues.

This may appear as swelling around the:

• Ankles

• Feet

• Lower legs

You may notice that shoes feel tighter than usual or that your socks leave deeper marks around your ankles.

But kidney disease isn't the only possible cause. Heart conditions, liver disease, certain medications, prolonged standing, and problems with the veins can also cause leg swelling.

Persistent or unexplained swelling deserves medical evaluation.

2. Puffy Eyes, Especially in the Morning

Another possible visible change is puffiness around the eyes.

When the kidneys are damaged, they may allow excessive amounts of protein—particularly albumin—to escape into the urine.

Low blood levels of albumin can contribute to fluid moving into surrounding tissues.

The result can be noticeable puffiness around the eyes.

Morning puffiness can have many other causes, including allergies, lack of sleep, crying, or normal fluid shifts.

But if it is persistent and occurs together with foamy urine, swelling elsewhere, or other symptoms, it's worth mentioning to a healthcare professional.

3. Foamy or Frothy Urine

This is one of the changes that should not simply be dismissed if it happens repeatedly.

Urine can sometimes look foamy when it hits the toilet water, particularly if the stream is forceful.

But persistent excessive foam or froth can be associated with protein in the urine, known as proteinuria or albuminuria.

Healthy kidneys normally prevent significant amounts of albumin from passing into urine.

Damage to the kidney's filtering units can interfere with that process.

Importantly, occasional bubbles do not automatically mean kidney disease.

But if your urine repeatedly looks unusually foamy, especially if the change is new, a simple urine test can help determine whether protein is present.

4. Blood in the Urine

Blood can sometimes make urine appear:

• Pink

• Red

• Brown

• Tea-colored

• Cola-colored

This is called hematuria.

Blood in urine can have many causes, including urinary tract infections, kidney stones, medications, prostate problems, and kidney disease.

It should not automatically be assumed to be a kidney problem.

At the same time, visible blood in the urine should not be ignored.

A healthcare professional can determine whether the blood is actually coming from the urinary tract and identify the appropriate next steps.

5. Very Dark or Unusually Concentrated Urine

Dark urine can occur simply because you haven't consumed enough fluid.

Urine naturally becomes more concentrated when you're dehydrated.

Certain foods, vitamins, and medications can also change urine color.

However, persistent unusual discoloration—especially when accompanied by blood, pain, reduced urine output, swelling, or other symptoms—deserves attention.

The important thing is to look for a persistent change from your normal pattern, rather than reacting to one isolated episode.

6. Noticeably Pale or Grayish Skin

Advanced kidney disease can contribute to anemia, partly because damaged kidneys may produce less erythropoietin, a hormone involved in stimulating red blood cell production.

Anemia can make someone look unusually pale.

The skin may appear less vibrant than usual, particularly in the face, lips, or inside the lower eyelids.

Paleness has many possible causes, including iron deficiency, blood loss, nutritional deficiencies, and other medical conditions.

A blood test is needed to determine whether anemia is actually present.

7. Dry, Itchy Skin

Persistent itching can occur in people with advanced kidney disease.

When kidney function becomes significantly impaired, waste products and changes in mineral and hormone balance can contribute to skin problems and itching.

The skin may also become dry.

However, itchy skin is extremely common and can result from eczema, allergies, medications, dry weather, liver conditions, and many other causes.

If itching is persistent, widespread, unexplained, or accompanied by other symptoms of kidney dysfunction, talk with a healthcare professional.

8. Skin That Appears Unusually Dry or Flaky

Dry skin alone isn't a reliable indicator of kidney disease.

Cold weather, hot showers, harsh soaps, dehydration, aging, and dermatological conditions can all cause dryness.

But significant kidney disease can sometimes be associated with dry, itchy skin.

If dry skin develops together with swelling, fatigue, changes in urination, or persistent itching, a medical evaluation may be appropriate.

9. Changes in Urination Frequency

Your normal urination pattern can vary depending on how much you drink, medications, weather, physical activity, and other factors.

But a noticeable and persistent change deserves attention.

Some people with kidney problems may experience more frequent urination, particularly at night.

Others with severe kidney dysfunction may produce significantly less urine.

Neither pattern is specific to kidney disease.

For example, frequent urination can occur with diabetes or urinary infections, while reduced urine output can occur with dehydration or urinary obstruction.

That's why the context matters.

10. Waking Up Frequently to Urinate

Getting up once at night to urinate can happen normally, especially as people get older.

But repeatedly waking several times every night to urinate—particularly if this is a new development—may warrant investigation.

Nighttime urination, known as nocturia, can be associated with kidney disease because damaged kidneys may become less capable of concentrating urine.

However, it can also occur with:

• Enlarged prostate

• Diabetes

• Heart problems

• Sleep apnea

• Certain medications

• Drinking large amounts of fluid before bed

Persistent nocturia should be discussed with a healthcare professional rather than automatically attributed to aging.

11. Unexplained Puffiness or Rapid Changes in Body Fluid

Kidney problems can affect the body's ability to maintain appropriate fluid balance.

This may result in swelling that develops in more than one area.

You might notice:

• Rings becoming tighter

• Shoes fitting differently

• Puffy eyelids

• Swollen ankles

• Rapid increases in body weight

A sudden increase in weight over a short period can sometimes reflect fluid retention rather than an increase in body fat.

But fluid retention has many possible causes, so it should be assessed in context.

12. Muscle Cramps or Twitching

Kidney disease can affect the balance of minerals and electrolytes such as calcium and phosphorus, particularly when kidney function becomes significantly reduced.

As a result, some people may experience: