Diuresis is an analysis that closely observes the state of urine. How to interpret it? What are the signs of too much or too little diuresis? Normal values, causes… Professor Christophe Legendre, nephrologist and head of the kidney transplant department at Necker hospital, provides clear benchmarks for understanding this essential parameter of kidney health.
Diuresis is an essential analysis to assess kidney function and the body’s water balance. “It is measured to look for the causes of oliguria (abnormally low urine flow) and polyuria (abnormally high urine flow), which raises suspicion of kidney disease“, explains Professor Christophe Legendre, nephrologist and head of the kidney transplant department at Necker hospital, to the Journal des Femmes. Measured in the hospital as in a city laboratory, it allows certain anomalies to be quickly detected. Here are the benchmarks to know to understand its analysis results.
What is diuresis?
Diuresis is the volume of urine produced by the kidneys over a given period of time, usually 24 hours. This simple indicator makes it possible to assess the functioning of the kidneys and the body’s water balance. Diuresis can be normal, insufficient (oliguria or anuria) or on the contrary too high (polyuria), depending on the quantity of urine emitted. Diuresis measurement is based on urine collection over 24 hours. The patient must urinate upon waking up without saving these first urines, then collect all the urine emitted during the day and night in a container, until the next morning at the same time. The total volume is then measured. In certain cases, additional analyzes can be carried out on this sample (dosage of sodium, potassium, creatinine or glucose) in order to refine the diagnosis. In a hospital environment, diuresis can also be monitored hour by hour, particularly in patients on a drip or in intensive care.
What is a normal diuresis in 24 hours?
“Diuresis is considered normal when the volume of urine emitted per 24 hours is between 500 and 3000 ml. Below 500ml/day, we are talking about of oliguria. Beyond 3000ml/day, there is question of polyuria“replies Professor Christophe Legendre, nephrologist and head of the kidney transplant department at Necker hospital, to Journal des Femmes.
Nocturnal diuresis: why?
Nocturnal diuresis corresponds to an increase in urine produced during the night, responsible for frequent waking up to urinate, called nocturia. It can be linked to several factors. With age, the body concentrates urine less well at night. In men, an enlarged prostate is a common cause. It can also be associated with certain diseases such as diabetes, heart failure or kidney problems. Taking diuretics, heavy consumption of drinks in the evening (water, alcohol, coffee) or sleep disorders can also contribute to this phenomenon. When these awakenings become frequent or bothersome, medical advice is recommended to identify the cause.
How to calculate diuresis?
Calculating diuresis involves collecting urine over 24 hours in a single containerhaving previously emptied the bladder of the first urine of the morning. The dates and times of urinary production must be noted until the next day.
What causes high diuresis?
We speak of high diuresis, that is to say polyuria, when the urinary volume exceeds 3 liters over 24 hours. The most common causes of polyuria are:
- diabetes. Diabetes is associated with greater secretion of glucose in the urine and increased diuresis;
- taking diuretic medications ;
- potomania or “primary polydipsia” (excessive water consumption).
Other causes must be considered, such as diabetes insipidus, certain kidney damage or problems with urine concentration.
What are the causes of insufficient diuresis?
Insufficient diuresis, called oliguria, may be linked to dehydration, reduced perfusion of the kidneys (in cases of hemorrhage or heart failure), acute or chronic kidney damage, or an obstacle in the urinary tract (such as stones). Certain medications can also reduce urine production.
What is osmotic diuresis?
Osmotic diuresis is a common mechanism in poorly controlled diabetes. When blood sugar exceeds approximately 1.8 g/L, the kidneys are no longer able to reabsorb all of the filtered glucose. Glucose is then eliminated in the urine and takes with it water and electrolytes (sodium, potassium, etc.). This phenomenon increases urinary volume and can cause dehydration if the losses are not compensated.
Thanks to Professor Christophe Legendre, nephrologist and head of the kidney transplant department at Necker hospital
