Polyuria: Symptoms, Causes & Treatment

Polyuria means producing and passing more than 3 liters of urine in 24 hours. It causes a person to urinate very frequently throughout the day and to pass unusually large amounts of urine each time.

Polyuria can be caused by drinking too much water, eating excessive protein, diabetes mellitus, diabetes insipidus, or hyperparathyroidism. Depending on the underlying cause, it may also be accompanied by symptoms such as weight loss and weakness.

Treatment for polyuria is usually managed by a nephrologist, endocrinologist, or primary care provider. It depends on the underlying cause and may involve reducing water or protein intake and/or using medication.

Main symptoms

The main symptoms of polyuria are:

• Passing large amounts of urine.

• Going to the bathroom several times a day to urinate.

• Waking up more than once during the night to urinate.

Depending on the cause, polyuria may also be accompanied by other symptoms, such as weight loss, increased appetite, and extreme fatigue (tiredness), which may suggest conditions such as diabetes mellitus and hyperparathyroidism.

According to the CDC, symptoms of diabetes can include frequent urination, increased thirst and hunger, weight loss without trying, and fatigue.

Confirming a diagnosis

Polyuria is diagnosed by a nephrologist, endocrinologist, or primary care provider based on symptoms, health history, and lab tests.

Main tests

The main test to confirm polyuria is a 24-hour urine test, which shows urine output greater than 3 liters per day in adults and more than 2 to 2.5 liters per day in children.

A provider may also order blood tests to check electrolyte levels, since these may be abnormal.

Other tests may include blood tests to check kidney function and blood glucose, a fluid restriction test, and imaging exams to evaluate the kidneys and bladder.

Possible causes

The main causes of polyuria are:

1. Drinking too much water

Polyuria caused by drinking too much water does not always mean there is a health problem. In general, it is the body’s response to excess fluid intake.

Too much fluid may also come from drinking large amounts of coffee, tea, soda, or alcohol, for example.

In some cases, however, drinking too much water may be caused by brain injuries related to accidents or may be linked to conditions such as anxiety and schizophrenia.

How to treat: If the urine is very pale or clear, it may help to slightly reduce the amount of water you drink during the day. In general, urine should be light yellow, which usually suggests adequate hydration.

However, if there is a history of head injury or symptoms such as excessive worry, nausea, or vomiting, it is important to see a primary care provider for an evaluation.

2. Too much protein in the diet

Eating too much protein, without advice from a doctor or dietitian, can contribute to polyuria.

This may include protein supplements, such as powdered formulas, cereal bars, and drinks used by athletes, as well as high-protein foods such as meat and eggs.

This usually happens because the body needs extra water to dilute the urine and remove the substances formed from excess protein, which are normally cleared by the kidneys.

How to treat: Protein supplements should be used with guidance from a sports medicine doctor or registered dietitian so they are not taken in excess.

It is also recommended to avoid eating too much protein by following a more balanced diet.

3. Diabetes mellitus

Polyuria may be caused by diabetes mellitus and is related to excess glucose in the blood.

Normally, the kidneys keep glucose from being lost in the urine. When blood sugar becomes too high, they can no longer do this completely, so glucose spills into the urine and drags water with it, leading to polyuria.

Although this symptom often appears in people who do not yet know they have diabetes, it can also occur in those who are already diagnosed but not properly treated and have poorly controlled blood sugar.

How to treat: If diabetes is suspected, it is important to see a primary care provider or an endocrinologist for evaluation. According to the National Institute of Diabetes and Digestive and Kidney Diseases, blood glucose and HbA1c are two of the main tests used to diagnose diabetes.

If diabetes is confirmed, it is important to follow the treatment prescribed by your doctor and adopt a healthy diet that is low in sugar.

4. Diabetes insipidus

Diabetes insipidus is usually caused either by low production of antidiuretic hormone, which normally helps reduce water loss in urine, or by the kidneys not responding properly to this hormone. This disruption leads to polyuria.

In this case, symptoms such as extreme thirst and tiredness are common, and some people may also have headache, nausea, and vomiting.

Although it is sometimes caused by a kidney problem, diabetes insipidus may also be triggered by brain injury, autoimmune disease, infections, or tumors.

How to treat: If diabetes insipidus is suspected, it is important to see an endocrinologist to confirm the diagnosis and start the most appropriate treatment, which may include a low-salt diet and a synthetic antidiuretic hormone.

5. Use of diuretics

Diuretic medicines, such as furosemide and spironolactone, are used to remove excess fluid from the body.

Because of this, if you are taking one of these medicines, it is normal to urinate more during the day.

These medicines are usually prescribed by a healthcare provider to treat conditions such as high blood pressure or heart failure, and they should not be used without medical guidance.

How to treat: If a doctor has prescribed you a diuretic but frequent urination is very bothersome, talk to them about whether the dose can be reduced or the medication changed.

6. Pregnancy

Urinating more often during pregnancy is usually normal because hormonal changes increase blood volume and make the kidneys work harder.

As pregnancy progresses, the growing uterus also presses on the bladder, so it cannot expand as much, causing a pregnant person to feel the need to urinate more frequently during the day.

How to treat: Frequent urination in pregnancy is usually normal. To help reduce it, a pregnant person can avoid drinks that stimulate urine production, such as coffee and tea, and choose water instead.

However, if symptoms like tiredness, weakness, and extreme thirst occur, it is important to see an obstetrician, as these may be signs of diabetes insipidus.

7. High calcium in the blood

High calcium in the blood, also called hypercalcemia, usually occurs in people with hyperparathyroidism and is defined by blood calcium levels above 10.5 mg/dL.

In addition to causing a major increase in urine volume, hypercalcemia may also cause drowsiness, extreme fatigue, nausea, and frequent headaches.

How to treat: If high blood calcium is suspected, it is important to see a primary care provider for an evaluation and to start treatment.

Treatment depends on the cause and may include medicines such as bisphosphonates and phosphate supplements.

8. Low potassium in the blood

Low potassium levels in the blood, called hypokalemia, can affect kidney function and lead to polyuria.

Besides excessive urination, other symptoms of hypokalemia include increased thirst, extreme tiredness, or frequent muscle cramps.

How to treat: Treatment is guided by a primary care provider or nephrologist, who may recommend potassium supplements, a potassium-rich diet, and ongoing monitoring of blood electrolyte levels and kidney function.

9. Urinary tract infections

Urinary tract infections (UTIs), such as cystitis or pyelonephritis, may increase urine volume and frequency, causing polyuria.

Other symptoms include very dark urine, cloudy urine with a strong odor, blood in the urine, abdominal pain, and fever.

How to treat: Treatment should be guided by a urologist or nephrologist and usually involves antibiotics to treat the infection.

10. Kidney problems

Some kidney problems, such as early-stage chronic kidney disease, acute kidney failure, or polycystic kidney disease, may cause polyuria.

This is because these conditions can affect the kidneys’ ability to concentrate urine or reabsorb electrolytes, which increases urine volume and output.

How to treat: Treatment should be guided by a nephrologist and may involve dietary changes, medications, hemodialysis, or even surgery in cases of polycystic kidney disease.