Diuresis refers to the volume of urine emitted per 24 hours. When and how to monitor it? What does too low a volume mean? Too high a volume? When to measure urine output? We offer you here, an inventory with Professor Christophe Legendre, nephrologist and head of the renal transplant service at Necker hospital.

Diuresis, also called urine output, is the amount of urine that is emitted per 24 hours.

Anuria

We speak of anuria when the diuresis is very weak, or if it is really zero, that is to say that there is no urine. “This situation is observed in subjects who have only one kidney, and who have a stone inside it which obstructs their excretory tract. They won’t be able to urinate at all. This can also be seen when a renal artery becomes blocked, for example, ”explains Professor Christophe Legendre.

L’oligurie

In this situation, the patient urinates less than normal, but still more than in anuria. In general, we speak of oliguria when the diuresis is less than 500 ml per 24 hours. “It is indicative of either kidney disease or kidney perfusion disease.

Polyuria

In this situation, the patient urinates too much, usually more than 3 liters per day.

The two main causes of polyuria are:

• polyuria in diabetics: diabetes leads to greater excretion of glucose in the urine, which increases the amount of diuresis;
• some psychiatric illnesses, such as potomania, are accompanied by excessive water consumption.

The normal rate of diuresis is between 500 and 3000 ml per 24 hours.

“Diuresis is measured in subjects who are looking for kidney disease and this for several days.”

The typical course of an exam

“The examination consists of urinating in a jar or a bottle of water for a day, and returning with his doctor to assess the volume over 24 hours,” says the specialist.

Depending on the symptom (anuria, polyuria or oliguria), the doctor will make diagnostic hypotheses and will try to determine why the patient is urinating too much or not enough.

Dr. Legendre is also keen to put an end to a received idea: “you have to get out of the very widespread idea that when you have kidney disease, you have to drink a lot. There is only one case in which it is useful is when the person has kidney stones because it dilutes a lot and prevents them from growing too fast. In general, let’s not forget that the body is well made and that, when we are thirsty, it sends us a signal ”.