What is polyuria?

Polyuria is a medical term to refer to the increase in urine production. In order to talk about polyuria, the body should produce more than three liters a day of urine in an adult, and more than two and a half liters in twenty-four hours in a child.

There are other similar terms, but they don't mean the same. For example, Poisoning is urinating several times a day, although with a normal amount of fluid in the total. On the other hand, we have nocturia, which is urinating at night interrupting sleep to do so.

There may be polyuria with nocturia, or polyuria with polaquiuria, but it is not the same. As well as there can be an increase in the volume of urine without another accompanying sign. In any case, we are facing a symptom and not a disease itself. To know the underlying disease, you have to reach the diagnosis.

The amount of urine produced in twenty-four hours depends on three factors:

  • Ingested: how much liquid we enter our body.
  • The substances to be removed: Urine is a mechanism of the human body to take out elements that have no use. The amount to be excreted will be one more factor.
  • Renal function: Urine is produced in the kidneys and depends on the ability of these organs to work.

General causes of polyuria

Let's first name the general causes of polyuria to explain later, in detail, some diseases that are the most frequent cause of the symptom. Among these general causes, we have some associated with everyday and passenger events and others more persistent:

  • Increased fluid intake: Obviously, if the fluid we drink in one day increases, the body will need to remove it. In this case, we will be facing a passing and benign polyuria.
  • Increase in salt intake: Salt is a substance capable of dragging water, that is, of associating with the body's water and taking it to the kidney to remove it from the body. When very salty foods have been ingested, an increase in the volume of urine is expected. It is also a momentary polyuria.
  • Urine stimulating drinks: certain liquids have the ability to increase urinary volume, like beer, some teas and caffeine.
  • Environmental cold: when it is cold in the environment and the body registers it, vasoconstriction occurs, that is, the caliber of the body's arteries decreases. By narrowing the arteries, there is less room for the blood they contain, and the way to get rid of that excess fluid is to increase the urine.
  • Use of diuretics: For some pathologies, doctors indicate medications known as diuretics (furoseminda or hydrochlorothiazide, for example). These drugs increase the volume of urine producing polyuria. It can be an expected treatment effect or an adverse effect.

Keep reading: Sugar or salt, which is worse in excess

Specific diseases that cause polyuria

As we advance, after describing the general causes, we will now name four diseases that have polyuria as a symptom. In these diseases medical control is very important, since polyuria can be a big problem.

Although polyuria is another symptom in the context of these pathologies, when it becomes uncontrollable it causes added problems. Even so, the goal will always be to solve the underlying disease.


It is considered, within diseases, the most common cause of polyuria. Classically it has been described that the triad of polyuria, polydipsia – increased thirst – and polyphagia – increased appetite – is the initial warning of the pathology.

In diabetes, polyuria responds to the body's need to get rid of excess glucose. With so much sugar circulating in the blood, the only way to escape is to excrete it with urine, increasing its production. Hence the classic polyuria of these patients.

Heart failure

In heart failure, the heart is unable to push the necessary amount of blood to the whole body. It becomes an insufficient organ because it does not have enough strength to perform its contraction work.

It is common for patients with heart failure to have polyuria because this failure in the circulation produces fluid accumulation. The body removes that excess fluid through the urine; Many times, increasing the night volume.

Keep discovering: Heart failure

Arterial hypertension

Hypertensive patients manifest an increase in the amount of urine when they are not medicated, or when the control of their disease is not good. Sometimes, before a silent disease, such as high blood pressure, the only sign is polyuria.

High blood pressure values ​​affect kidney function, changing the way they filter blood and produce urine. Therefore, production is increased. In addition, mechanisms similar to those of heart failure are also involved.

Renal insufficiency

In proportion, there are not many people with kidney failure, but the pathology is very serious. In these cases, The kidneys are insufficient because they are not able to adequately filter the blood for proper urine production. Given this poor filtration, not only substances that must be removed from the body, but also useful substances and water are lost.

Renal insufficiency may be a final and complicated stage of other pathologies., such as diabetes, or an entity itself produced by poorly resolved infections, autoimmune attacks of the organism or malignant tumors.

Conclusion on polyuria

Polyuria is a symptom to pay attention to. If we know that we have eaten salty or we have been cold, we can remain calm and wait for the sign to disappear on its own. However, if it has become persistent, we should consult.

Medical professionals will know how to request the necessary studies to reach the diagnosis of the underlying causes of our polyuria. Once the origin is found, the corresponding treatment is established.