What is Polyuria—and Why Do I Pee So Much?

Causes of excessive urination and how it's diagnosed and treated.

If you're emptying your bladder more often than usual and peeing a lot each time, there could be a simple reason: maybe you've increased your fluid intake recently or have been drinking lots of diuretic beverages, such as caffeinated coffee or soda.

But once you've ruled out the obvious causes and lifestyle habits, it's worth asking yourself if your increased urination could be medically related; there are several common health conditions that can cause an uptick in urine production and voiding (and some less-than-common ones as well).

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Here's what you need to know about one of the major reasons why you could be experiencing excessive urination, also known as polyuria, as well as what you should do if you think you have it.

What Is Polyuria?

According to S. Adam Ramin, MD, urologist and medical director of Urology Cancer Specialists in Los Angeles, polyuria means having frequent or multiple bouts of urination in a 24-hour period with large amounts of urine each time.

A person with polyuria may produce upwards of 3 liters of urine per day, according to research published in 2015 in the American Journal of Kidney Diseases.

That's much higher than the average output of 800 milliliters to 2 liters per day, according to the National Library of Medicine's resource MedlinePlus.

You should note that it is not the same as nocturia, or needing to wake up in the night to pee. Although, polyuria is a common cause of nocturia, according to the Urology Care Foundation.

There are other causes of nocturia in which your body is not overproducing urine—you just have the urge to go more frequently (this can happen for a variety of reasons, most often incomplete voiding due to enlarged prostate and overactive bladder).

And there's one more wrinkle: Some people with polyuria only have increased urination at night, said Dr. Ramin. It's called nocturnal polyuria.

What Causes Polyuria?

Because polyuria isn't just urinary frequency, or feeling an urge to go more frequently, it's necessary to figure out what's causing the increase in urine production in order to manage your polyuria.

Most of the time, said Dr. Ramin, uncontrolled diabetes mellitus, both type 1 and type 2, is the culprit. Diabetes mellitus is a chronic disease involving elevated blood glucose, or blood sugar.

"If a person all of a sudden develops increased urination, it's important to see if they have uncontrolled diabetes," Dr. Ramin said. It may be difficult for you to determine whether you have urinary frequency versus polyuria, which is why you should see a healthcare provider, explained Dr. Ramin.

The high occurrence of polyuria in people with diabetes comes down to blood glucose. According to the diabetes research organization JDRF, excess sugar in your blood can't be processed by the kidneys and reabsorbed back into the bloodstream; instead, it draws more water into your urine and promotes excess urine production.

There is another kind of diabetes, a rare form called diabetes insipidus, that can also be responsible for polyuria, explained the National Institute of Diabetes and Digestive and Kidney Diseases. In diabetes insipidus, glucose levels are normal, but the kidneys can't properly concentrate urine.

Diabetes insipidus can cause both excessive thirst, which leads to extreme water intake, and a deficiency of something called vasopressin, an antidiuretic hormone (ADH) that promotes water conservation in your kidneys and helps to balance the amount of fluid in your body.

Diabetes mellitus, diabetes insipidus, or just drinking excess fluids are the most common causes of polyuria, per MedlinePlus.

Other conditions that are associated with polyuria, according to MedlinePlus and other experts, include:

  • Kidney disease or kidney failure
  • Medications, such as diuretics or lithium
  • High or low calcium levels in the body
  • Sickle cell anemia
  • Congestive heart failure
  • Varicose veins

Polyuria is also more common in older adults, especially women, said Mark Ellerkmann, MD, director of the Urogynecology Center at Mercy Medical Center in Baltimore. "ADH makes your kidneys make less urine; it's secreted so you're not up all night peeing," Ellerkmann explained. "But as you get older, you secrete less."

What Are the Symptoms of Polyuria?

In many cases, you may experience what Dr. Ramin called an acute onset of polyuria: "From a symptom standpoint, this means a person has been doing okay and then all of a sudden they're urinating more often in the daytime, more than ever before."

Again, it's important to pay attention to whether you're actually peeing an unusually large amount of urine or simply feeling like you need to go more frequently. If you're using the bathroom several times per hour but only urinating a small amount each time, it's more likely to be urinary frequency or nocturia.

Increased voiding is a symptom of polyuria, though excessive urination can cause its own sub-symptoms as well, including excessive thirst (if you're urinating a lot, you'll feel more thirsty than usual) and nighttime wakings to urinate.

How Is Polyuria Diagnosed?

Drs. Ellerkmann and Ramin said a diagnosis of polyuria begins with identifying the source of the problem—polyuria versus urinary frequency, an important distinction for determining treatment. In this case, the most important diagnostic tool is information.

Dr. Ellerkmann said the results of a urine frequency-volume chart, or 24-hour voiding diary, can help determine if you have urinary frequency or nocturia due to low-volume voiding, polyuria due to an excess volume of urine, or both.

For instance, if you are urinating frequently throughout the day but only producing an average or below-average amount of urine, the diagnosis will likely exclude polyuria.

On the other hand, if you're urinating frequently and it's adding up to more than the average amount, that's a good sign for your doctor that you're dealing with a high volume of urine, not just a high frequency.

There is another way, Dr. Ellerkmann said, your doctor may try to distinguish between the frequency versus volume of your voiding: "Measuring post-void residual urine [in the bladder] by catheterization or bladder ultrasound can be helpful in diagnosing bladder obstruction and urinary retention."

In other words, your healthcare provider may ask you to undergo diagnostic testing in-office or at a hospital or clinic that involves measuring the amount of urine left in your bladder after you void.

Less than 75 milliliters is considered normal, per Dr. Ellerkmannn, but residual urine totaling 200 milliliters or more is considered abnormal (and might prompt a polyuria diagnosis).

How Is Polyuria Treated?

Polyuria itself doesn't come with its own treatment plan and there are no specific medications to treat polyuria. Instead, you and your doctor will focus on better managing the condition or conditions causing you to pee so much.

"The treatment is mostly driven by the root cause of the problem," said Dr. Ramin. "You determine the underlying cause and address any uncontrolled conditions, like diabetes or congestive heart failure."

For example, said Dr. Ellerkmann, when you combine the prevalence of varicose veins in older women with the changes in ADH production, you end up with many older women producing extra urine—especially at night. "You build up swelling in your lower legs, go to bed, and put your legs up, and then your body tries to mobilize all that fluid back into your vascular tree."

This process, Dr. Ellerkmann added, involves producing more urine in the kidneys and causing more frequent voiding. In the case of varicose veins, the"treatment" for polyuria would involve managing your edema (tissue swelling); this might include wearing compression stockings during the day to improve your circulation and reduce swelling.

If your healthcare provider feels that medication might be a necessary component of your treatment, there are drugs given to people with related conditions, like overactive bladder or enlarged prostate, which may help.

Still, with polyuria, the best treatment involves finding out why your body is producing so much urine in the first place and focusing that treatment on the source of the problem.

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