The medical definition of anuria is the following: urinary tract disorder in which the subject does not emit urine, or in any case emits less than 100 mL of it in 24 hours. As we can well understand, this is a completely insufficient quantity compared to that emitted under physiological conditions, which is between 1 and 2 liters per day.
Therefore, this condition represents a real medical emergency that must be treated with extreme speed due to the harmful outcome that it can entail.
Anuria can be attributed to many factors, as we will see, but essentially it can be due to a reduced production of urine or to an obstruction of the urinary tract that does not allow it to escape during the act of urination.
Therefore, for practical reasons the causes of anuria are divided into:

  • pre-renal: if the anuria is due to the fact that the kidney does not reach an adequate amount of blood to be filtered to produce urine;
  • kidney:when the damage is localized in the kidney and this organ does not perform its filtration function;
  • post-renal: in which the problem results in a blockage of the urinary tract.

is a symptom to which you must pay close attention, many times it can in fact indicate a disorder of moderate or serious clinical interest, therefore it is a condition that should never be underestimated and that must be promptly addressed to medical attention.
Symptoms associated with anuria progressively progress with the onset of the condition, and if the subject continues to drink fluids despite being unable to urinate, generally life-threatening compromises occur over the course of 72 hours.
Lack of diuresis leads to a progressive rise in blood nitrogen values ​​(azotemia), nausea, alterations in the respiratory rhythm and heart rate, diffuse edema, severe impairment of the hydro-saline balance, metabolic alkalosis, drowsiness and lack of strength that lead to a condition that takes the name of uremic coma .
Furthermore, urinating little and therefore having an expulsion of urine that occurs more rarely than normal, facilitates bacterial proliferation of the urinary tract, effectively promoting infection of the lower urinary tract.
Not surprisingly, girls who suffer from frequent episodes of cystitis are recommended to drink more, as the increased intake of fluids stimulates diuresis, which allows through the jet of urine to expel part of the bacterial load.
Similarly, girls suffering from frequent cystitis are invited to urinate after sexual intercourse, so that, thanks to the mechanical action of diuresis, part of the bacteria that have entered the urethra and reached the bladder are washed away.

What are the causes of anuria
For ease of reading and understanding, we have decided to report the causes of anuria based on localization, referring to what is illustrated in the previous paragraph.

Pre-renal causes
The damage in this case is upstream of the kidney. This organ receives a poor blood perfusion, therefore it cannot perform its blood filtration function and as a consequence there is no urine production.
Under which conditions there is a drastic reduction in the blood supply to the kidneys, such as to cause anuria
The fundamental requirement is that the patient has lost a large amount of fluids, therefore pre-renal anuria generally arises as a result of a strong bleeding, burns, dehydration, hypotension and numerous episodes of vomiting and diarrhea following an infection.
Anuria can also occur in people who take diuretic drugs as a treatment for hypertension.

Kidney causes
In these cases, anuria is a manifestation resulting from a renal pathology that does not allow this organ to perform its function of filtering the blood , and therefore of producing urine.
Let’s see which pathologies are most common:

  • Ischemia : there is a reduction in blood flow to the kidney, mainly caused by a partial obstruction of a blood vessel;
  • Necrosis : phenomenon caused by exposure to toxic substances for the kidney called nephrotoxic. These substances include some antibiotics, some non-steroidal anti-inflammatory drugs (NSAIDs) or the contrast medium used in some instrumental diagnostic investigations. For this reason, before carrying out, for example, an MRI scan, a recent analysis of creatinine is required (evaluated through a simple blood sample), because it provides a valuable indication of the state of health of the kidneys;
  • Glomerulonephritis: it is an inflammatory state of the kidney caused mainly by a bacterial infection (which takes the name of pyelonephritis), or by an autoimmune disease that affects the structure of the kidney called the glomerulus. Structure, the latter, involved in the process of urine production.

Post-renal causes
This category includes cases in which the kidneys have produced urine regularly, but this cannot escape due to an obstruction of the urinary tract (ureters, bladder or urethra). But what causes the obstruction

  • Kidney stones: these are crystallized formations that form in people affected by kidney diseases or who follow a high- protein diet . The stones obstruct the urinary tract and can prevent the outflow of urine to the outside;
  • Prostatic hypertrophy: a pathology of strong clinical interest that generally affects men over 50 years of age. It is a slowly evolving neoplastic process that leads to an increase in the volume of the prostate gland. The prostate gland is placed inferiorly to the bladder and its increase in size and stiffening presses on the bladder, generating the sensation of having to urinate frequently, but at the same time it can block the transit of urine towards the urethra;
  • Bacterial infections: the most common are cystitis (in the female gender), urethritis and prostatitis (in the male). There are phenomena of inflammation, therefore of inflammation, which can make the passage of urine very difficult;
  • Neoplasms: their mass obstructs the lumen of the ureter or urethra, preventing the passage of urine.

How the diagnosis is made
We have previously seen how important it is to intervene promptly in case of anuria .
This is because it is a symptom often indicative of a pathological condition and which in a short time can lead to a serious compromise of the patient’s clinical conditions, up to a state of real danger for his life.
If we add to this that the diagnosis is rather demanding, as it must investigate all the possible causes seen above, it is clear how fundamentally important it is to entrust the assessment of the case only to a doctor, generally a specialist in internal medicine. or in nephrology, or in urology.
In any case, it is recommended not to waste time looking for remedies to the problem on the internet, or resorting to do-it-yourself interventions. The seriousness of the condition is reaffirmed and the need to resort to medical intervention as quickly as possible.

What procedures are usually performed in the diagnosis of anuria
The doctor ascertains how long and that the subject is unable to urinate and preliminarily assesses the level of metabolic impairment on the patient’s state of well-being, verifying whether he is lucid and cooperative, if the frequency respiratory and cardiac are impaired, if you have edema, drowsiness and physical fatigue.
It is also of fundamental importance to know if the patient has lost a lot of fluids as a result of haemorrhage, burns, or if through vomiting and diarrhea due to an infection or intoxication.
The diagnostic procedure proceeds differently from case to case, but usually a blood sample is essential through which to evaluate the levels of azotemia, alterations in the hydro-saline balance and traces of urinary infection. Furthermore, the presence of metabolic acidosis (a condition indicative of renal pathology) is assessed by means of a hemo-gas analysis .
An ultrasound will be useful in verifying the presence of kidney stones, an echocolor-doppler instead will evaluate if there are pathological conditions in the renal veins and arteries.

What are the most effective
therapies The therapies in case of anuria must go to strictly target the cause triggering the problem and must therefore go to act at the pre-renal, renal or post-renal level, taking into account the individual factors of the subject (age, state of health, drug intake, concomitant pathologies).
Generally, if the patient has lost a large amount of fluids (pre-renal cause), a drip of physiological solution is given to restore the correct fluid supply.
If the cause is of renal origin, depending on the case, pharmacological therapies may be sufficient, but in conditions of severe renal insufficiency dialysis is necessary .
As for obstruction pathologies, if the cause is bacterial it is necessary to administer antibiotics, if instead the cause is due to stones, neoplasms or prostatic hypertrophy, surgery may be necessary.
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