An Overview of Polyuria (Excessive Urination)

Polyuria is when your body produces too much urine, more than 3 liters of urine a day for adults. It refers specifically to the amount of urine excreted daily, not the frequency of bathroom trips.

Polyuria is not a medical condition in itself, but it can be a symptom of other illnesses. Common causes include diabetes, kidney disease, and certain medications. It can also be caused by pregnancy, an electrolyte imbalance, excess caffeine, and drinking alcohol.

This article explains polyuria symptoms and causes. It also discusses how polyuria is diagnosed and treated.

Polyuria Symptoms

Polyuria literally translates to "urinating too much" and may be the only symptom one experiences. In general, an adult voids up to 2.5 liters of urine daily. If the amount excreted is more than 3 liters, it's considered abnormal.

Depending on the cause, there are other symptoms that can accompany polyuria. When the cause is either diabetes insipidus or diabetes mellitus, polyuria is usually coupled with excessive thirst (polydipsia).

Frequent urination, especially at night (nocturia), is often associated with polyuria, but it doesn't have to be.

Polyuria Causes

There are myriad causes of polyuria, ranging from drinking too much water to serious health complications like kidney failure. The following causes of polyuria are the most common.

Diabetes Mellitus

Diabetes mellitus is a condition caused by the body's inability to adequately control blood sugar, either because it is unable to properly manufacture insulin or a has resistance to the effects of insulin. Diabetes mellitus leads to higher osmolarity in the bloodstream because of increased sugar levels.

Diabetes Insipidus

Diabetes insipidus is completely different from diabetes mellitus and doesn't have anything to do with blood glucose levels. Instead, diabetes insipidus is related to polyuria directly in its connection to arginine vasopressin (AVP), an antidiuretic hormone.

Central diabetes insipidus is caused by a lack of arginine vasopressin secretion due to a neurological condition. Nephrogenic diabetes insipidus is due to failure of the kidney to respond to AVP. Central diabetes insipidus can be acquired from a medical or traumatic brain injury. Nephrogenic diabetes insipidus is usually inherited.

Diuretic Medications

Certain medications are designed to increase urination to treat conditions like congestive heart failure and high blood pressure. Those medications can lead to polyuria if the dosages are not correct. Your physician will adjust the dosing of your medications as necessary to avoid unnecessary urination.

Lithium

Lithium is a medication used to control mood disorders. It is almost entirely excreted from the body in urine and can have a profound effect on the kidneys in patients who take it regularly. Lithium can cause polyuria and polydipsia as a result of lithium-induced nephrogenic diabetes insipidus.

However, if polyuria is present and lithium is not discontinued, irreversible damage to the kidneys can cause permanent polyuria.

Alcohol or Caffeine Intake

Both alcohol and caffeine have known diuretic effects. Drinking either one to excess is capable of triggering polyuria to the point of developing dehydration. Alcohol is always a diuretic, even for people who drink alcohol on a regular basis. The diuretic effects of caffeine can decrease over time in people who regularly drink it.

Pregnancy

Polyuria is a common symptom in early pregnancy. It is caused by an increase in progesterone and human chorionic gonadotropin (HCG). Polyuria in pregnancy typically resolves after the first trimester.

Polyuria in the second trimester can be a sign of gestational diabetes. Talk to your healthcare provider if you are concerned about excessive urination during pregnancy.

Polyuria Diagnosis

Polyuria is a symptom rather than a medical condition in its own right. There is no actual diagnosis of polyuria. However, the underlying cause of polyuria can be diagnosed once the symptom appears. The process of diagnosis for each cause is different. In every case, the physician will begin with determining the time of onset of polyuria and whether it came on suddenly or gradually over time.

Diabetes Mellitus vs. Diabetes Insipidus

If the onset of polyuria follows a significant neurological issue, such as traumatic brain injury or stroke, it could be a symptom of central diabetes insipidus.

Polyuria and polydipsia are both signs of diabetes mellitus as well as diabetes insipidus. Both conditions are significant and require further tests. The physician will want to measure the patient's hemoglobin A1C, a blood test that retroactively measures the average blood glucose levels over the previous six months.

The physician most likely will also order a urine glucose test to see if the body is excreting sugar in the urine, a sign of diabetes mellitus.

Polyuria Treatment

The most effective treatment for polyuria is aimed at the underlying cause. For example, lithium-induced nephrogenic diabetes insipidus could potentially be treated by discontinuing the lithium. Polyuria caused by diabetes mellitus is likely to improve once the patient's blood glucose levels are controlled.

Polyuria that cannot be corrected by treating the underlying cause is often treated with one of several medications that come from many different classes. One hallmark of polyuria is the diluted nature of the urine produced—it's composed of more water than urine.

Some treatments for polyuria include giving a type of diuretic, which usually increases urine output because it improves the way urine is processed in the kidneys.

A Word From Verywell

If you suspect that you are urinating too much (or too often), it's time to contact your primary physician, especially if you are also always thirsty. Polyuria can be treated and is not dangerous in the short term. However, it's crucial to get it corrected so that any potential underlying condition doesn't go untreated. Rest assured that early intervention with polyuria, as with any health condition, is key to managing and treating your health in the best way possible.