Oliguria

Oliguria - a decrease in the volume of excreted urinary fluid - is not a disease, but only a symptom that indicates a malfunction in the body. This condition can be observed at any age, starting from the newborn period.

Oliguria is said if the average daily volume of urine is less than half a liter, while the norm is the excretion of about 1.5 liters of urinary fluid per day.

Epidemiology

Disturbed urination is the most common disorder related to the genitourinary tract. Over the course of a day, a healthy body can excrete approximately 1.5 liters of urinary fluid, which should account for about 75% of the fluid consumed in those 24 hours. The remaining 25% is excreted through the respiratory system, skin, and intestines. The frequency of urinary excretion is approximately 4-6 times per day.

Oliguria is said when the daily volume of urinary fluid does not exceed 400-500 ml, which can be due to various reasons.

Oliguria can be diagnosed at any age, in males and females equally. However, accurate statistics of this phenomenon are not kept, primarily because oliguria is not a disease, but only a symptom of other morbid and physiologic conditions. Nevertheless, it is believed that a decrease in daily diuresis is more common:

• in newborn infants (related to physiological features);
• in women (caused by hormonal changes, pregnancy or childbirth);
• in men with prostatitis or prostate adenoma.

Causes of the oliguria

So what is the cause of oliguria? In general, there are many such causes, and they can be conditionally divided into several types:

• Prerenal oliguria (not due to renal pathology);
• Renal oliguria (caused by renal pathology that can lead to the development of OPN or CKD);
• Postrenal oliguria (associated with impaired urinary outflow from the kidneys).

Causes of prerenal oliguria include:

• A sudden drop in blood pressure (shock hypotension, major blood loss, heart failure);
• Fluid loss due to heavy sweating, vomiting, frequent liquid stools, improper and unjustified use of diuretics, as well as a general deficit of fluid in the body due to insufficient intake;
• deterioration of renal circulation due to vascular stenosis, aortic atheromatosis, vasculitis, nephrosclerosis.

Renal oliguria is caused by:

• pathologies, mainly related to the renal tubular apparatus and manifested by structural and functional disorders (glomerulonephritis, nephritis in combination with systemic pathologies);
• diseases associated with damage to renal tubules and interstitial tissue (acute form of tubular necrosis, acute form of interstitial nephritis);
• Vascular diseases (systemic vasculitis, scleroderma).

The causes of postrenal oliguria are as follows:

• urinary tract stones;
• tumor processes affecting the ureter;
• Retroperitoneal fibrosis (Ormond's disease);
• other tumors that put pressure on the ureter;
• compression of the ureter by an enlarged uterus in women during pregnancy.

Acute renal failure is also accompanied by oliguria, with a total daily diuresis of less than 0.4 L (20 ml per hour). There is an absence or marked decrease in urinary fluid flow into the bladder. However, this is not always the case: some patients may even have an increase in diuresis. In such cases, neoliguric renal failure is said to occur. [1]

Pyelonephritis in acute form can also cause oliguria: in such a situation, other symptoms such as fever, pain in the lumbar region, proteinuria, bacteriuria, etc. Are necessarily present.

Risk factors

The appearance of oliguria is often associated with tumor processes and other pathological formations (strictures, concrements), parasitic diseases, inflammatory pathologies of the pelvic organs.

Patients with these disorders and conditions have an additional risk of developing oliguria:

• inflammatory processes affecting the bladder, brain and spinal cord, prostate, female reproductive system, urethra, respiratory organs;
• urolithiasis, renal tuberculosis, diabetes mellitus;
• neurological disorders;
• sharp hormonal fluctuations (puberty, pregnancy, PMS, menopause, etc.);
• Obesity or a sudden change in weight;
• pelvic or inguinal trauma;
• surgical interventions on abdominal and pelvic organs.

The above factors should be identified, treated or corrected, observed to take timely action. [2]

Pathogenesis

A decrease in the volume and rate of blood plasma glomerular filtration is noted in these disorders:

• Decrease in hydrostatic blood pressure on the capillary wall of the tubules less than 35-40 mmHg and decrease in systemic blood pressure values less than 80 mmHg. - For example, as a result of collaptoid, shock state, insufficient cardiac activity, significant blood loss. At the same time, the process of renal self-regulation is disrupted, and the rate of glomerular filtration decreases as blood pressure decreases.
• Increase in oncotic pressure of blood plasma more than 25-30 mmHg as a result of blood thickening in dehydration, infusion of colloidal solutions, as well as in pathologies combined with increased protein content in the blood.
• Spastic contraction of the delivering renal arterioles, or organic disorders in renal arterial and other vessels - e.g. Atherosclerosis, nonspecific aortoarteritis, fibromuscular dysplasia.
• Increased pressure of tubular ultrafiltrate in the capsule of the renal calf, exceeding 10-20 mm Hg. Column. This occurs against the background of delayed fluid reabsorption in the proximal tubules, plugging of tubules with particles of dead epithelium and blockage of the urinary tract with concretions, clots, etc.
• Limitation of the scale of the filtration surface of the tubules due to a decrease in the number of "working" nephrons.
• Deterioration of membrane-club permeability, which is associated with its compaction and reduced porosity against the background of inflammatory tubular pathologies (glomerulonephritis, diabetes mellitus).

Symptoms of the oliguria

The main symptom of oliguria is a decrease in the amount of urinary fluid: the person visits the toilet less often, and a small volume of urine is excreted during urination. If there are no other pathologies, there is no additional discomfort. For example, if oliguria is due to a banal low fluid intake throughout the day, or increased sweating, then there is no pathology: the frequency and volume of urine output normalizes as the drinking regimen is corrected.

A kidney disorder is spoken of if other early signs are present:

• painful urination;
• pain in the lumbar region, abdomen;
• difficulty urinating;
• intermittent jetting, weak jetting when the bladder is full;
• the appearance of blood, white flakes, pus in the urinary fluid;
• fever, chills, fever;
• nausea, digestive disorders.

The normal state of physiologic (not pathologic) oliguria occurs against the background of increased fluid intake and at the same time insufficient fluid intake into the body. Such oliguria is often called "false: it can be provoked by mental disorders, strict diet with restriction of drinks and liquid food, hot climate, high room temperature. Sometimes fluid intake is reduced intentionally - for example, in pancreatitis, diseases of the cardiovascular system, toxicosis in pregnancy. [3]

False oliguria can be transformed into a real pathology, and in such a situation the clinical picture is significantly expanded, other painful signs appear, mentioned above.

It is important to consult a doctor at the initial stage of the problem, when there are such symptoms against the background of a normal drinking regimen:

• oliguria lasts for more than 2 days;
• pain in the lower abdomen, groin or lower back;
• the fever's rising;
• the color and odor of the urinary fluid changes dramatically;
• pathologic discharge from the urethra (blood, pus, etc.).

Oliguria in children

To find out the cause of oliguria in preschool and school-aged children, some important points need to be clarified:

• how the child eats, what his drinking habits are;
• whether he or she is taking any medications (self-administration of medications by adolescents cannot be ruled out).

In first-time oliguria, the characteristics of the patient's urinary system prior to the onset of the problem (volume, frequency, etc.) should be identified. It is important to try to make a chronological connection between the decrease in daily urinary volume and diseases that are or have been present in the child. Possible exposure to toxic substances cannot be ruled out.

Monitoring of daily urine volume should be done at home after prior instruction to the child's family.

Pathologic oliguria in childhood may be associated with:

• with non-sugar diabetes;
• with chronic pyelonephritis;
• with acute glomerulonephritis;
• with renal tuberculosis.

Oliguria in newborns

Newborn babies often have a physiologic form of oliguria. Its appearance is due to the fact that babies in the first days after birth use little fluid, because the mother's lactation abilities are just getting better. In addition, most of the moisture the child's body removes with meconium - quite liquid fecal matter. Given this, do not be alarmed: it is important that the child generally feels normal.

However, parents should constantly monitor indicators such as the color of urine and feces, smell, turbidity or transparency of urine. It is important to realize that the baby is not yet able to ask for water and cannot tell you how thirsty he is. It is important to listen to his condition - especially in hot periods, or when the mother's milk production is insufficient. Control of the amount of fluid is also necessary when the baby has digestive disorders, which are accompanied by the release of liquid stools. In this situation, the main thing is to prevent dehydration.

Oliguria in pregnancy

Pregnant women are often diagnosed with a physiologic form of oliguria due to reasons such as:

• the pressure of the enlarging uterus on the ureters;
• redistribution of fluid to the placenta and amniotic fluid;
• correction of water-salt balance (sodium accumulation);
• increased tissue hydrophilicity (tendency to edema).

If the ureters are squeezed, the urinary fluid outflow is impaired. In addition, women during pregnancy often suffer from edema - not only external, but also internal edema, which is almost invisible externally.

Swelling is more common from about the 7th month of pregnancy, but some women experience the problem as early as the 4th or 5th month. Swelling is more pronounced in expectant mothers expecting twins or a large baby.

Swelling most often occurs in the lower extremities, and less often in the arms and face. Hidden or internal swelling is more dangerous and needs to be detected as early as possible.

Forms

As we have already mentioned, oliguria comes in several types, namely, prerenal, renal, and postrenal.

In addition, there are also such types of pathology:

• Acute oliguria is an acute disorder of urinary outflow from the kidneys to the bladder, which develops due to occlusion of the upper urinary tract. The cause may be urolithiasis, tumor processes, ureteral disorders.
• Physiologic oliguria is a state of decreased daily urine volume caused by physiologic factors such as insufficient fluid intake, excessive sweating, etc. Transient oliguria (the second name of physiologic oliguria) is a prerenal condition caused by a decrease in circulating blood volume.
• Severe oliguria is a pathologic state extremely close to anuria - that is, the complete cessation of urine excretion.

Complications and consequences

If no action is taken, pathological oliguria can be transformed into anuria: excretion of urinary fluid from the body is completely inhibited, resulting in the development of corresponding complications - in particular, renal failure.

Depending on the type of oliguria, with a prolonged pathological process, all sorts of negative changes occur, affecting all organs. The acid-alkaline balance, metabolism is disturbed. The main unfavorable consequences can be called the following:

• inhibition of renal blood flow;
• decreased fluid filtration;
• lymphatic dysfunction;
• disturbance of the trace elemental balance;
• blockage of renal function due to impaired processes of tissue respiration under the influence of intoxication.

To avoid the development of complications, it is recommended to seek qualified medical assistance in time. [4]

Diagnostics of the oliguria

The main direction of diagnosis in oliguria is the identification of the cause of the disorder. An important role in this is played by the collection of anamnestic data, as well as a thorough complete examination of the patient's body.

It is especially important to pay attention to those diseases that a person has had before:

• genitourinary diseases;
• prone to stone formation;
• abdominal diseases;
• tumor processes.

Often it is enough to take general blood and urine tests to make a correct diagnosis. In other situations, instrumental diagnostics is additionally performed. The entire diagnostic list may include:

• studying the history of the disease, determining the causes of a possible decrease in circulating blood volume (diarrhea, improper drinking, vomiting, taking certain medications, etc.);
• physical examination methods (assessment of skin elasticity, cardiovascular activity, pulse rate and blood pressure, abdominal palpation, etc.);
• blood chemistry;
• ultrasound examination of the urogenital system and abdominal organs;
• CT scan, renal scan, abdominal radiography;
• consultation of a proctologist, gynecologist, dermatologist, infectious disease specialist, allergist, endocrinologist.

During the examination of the patient, the doctor pays attention to the probable swelling - both pronounced and hidden. [5]

Auxiliary laboratory methods: urinalysis by Nechiporenko, assessment of total daily diuresis and daily protein excretion, Zimnitsky urine test, urine fluid culture.

Instrumental Diagnosis:

• ultrasound scan;
• retrograde pyelourethrography;
• renal arteriography;
• a review radiologic study;
• renal angiography;
• excretory urography;
• urotomography;
• CT SCANS, MRIS;
• Doppler.

To assess the functional capacity of the kidneys, it is advisable to perform radioisotope diagnostics, including scintigraphy and renography.

Differential diagnosis

As a variant of the term "dysuria", oliguria is one of the many variants of urinary disorders.

However, a decrease in daily diuresis can be classified as a violation of urinary fluid evacuation, even in combination with other pathological signs. To make an accurate diagnosis, the doctor always makes a "parallel" with similar diseases, as this directly affects the effectiveness of the prescribed treatment.

The pathologic conditions usually distinguished are:

• Stranguria - a difficult act of urination, which is accompanied by painful sensations, false urges;
• urinary retention, or ischuria - the inability to empty the bladder independently for mechanical or neurogenic reasons.

Such different pathologies as oliguria and anuria require differentiation. If oliguria is said when the daily volume of urine does not exceed 400-500 ml, anuria is a complete blockage of urine output (no more than 100 ml/day, that is, less than 5 ml per hour). Anuria belongs to the category of urgent urological pathologies and requires emergency medical care, often being a sign of severe failure of renal function.

Sometimes a patient may have a combination of such symptoms as oliguria-nycturia: during the daytime a person rarely visits the toilet, but at night the situation changes, i.e., nocturnal diuresis exceeds the daily diuresis. The physiological norm is considered that the night volume of urine should not exceed 30% of the daily volume. Otherwise, the patient has to wake up at night, which leads to the development of insomnia, deterioration of working capacity, etc. In this situation, it can be assumed that during the daytime the patient's bladder is not emptied completely, which leads to the need to empty it at night.

Symptomatic combination of oliguria-proteinuria is one of the characteristic features of the urinary syndrome: against the background of reduced urinary fluid outflow, the permeability of the tubular filter increases, the function of the tubule apparatus of protein reabsorption deteriorates. In more than 80% of cases, blood in the urine is also detected: oliguria-hematuria develops, which is due to increased permeability of capillary walls of the tubules. The term hematuria can be broadened: a small number of red blood cells in the urine is described as microhematuria, and a large amount of blood in the urinary fluid is described as macrohematuria.

Special attention should be paid to patients who purposely limit the amount of fluid (and sodium chloride) due to psychogenic or principled position. Such people should be explained the need to increase the volume of fluid intake, point out the risk of complications. [6]

Treatment of the oliguria

To normalize urine output and eliminate oliguria, it is necessary to influence the cause that provoked the malfunction. In general, the treatment scheme should include the following points:

1. Exposure and elimination of the original cause.
2. Restore the quality of blood circulation, correction of water-salt balance in the body.
3. Prevention and treatment of possible complications.

Drug therapy is mandatory, but drugs are prescribed based on the primary pathology. That is, there are no direct drugs for oliguria: treat the underlying disease that led to this disorder.

If oliguria is due to the development of pyelonephritis, glomerulonephritis, then treatment with medications is necessarily supplemented with diet therapy. In oncopathology and the formation of stones in the urinary system in the vast majority of cases, surgical intervention is performed.

Self-treatment attempts usually do not lead to a positive result. The use of any medication, including diuretics, must always be justified, so only a doctor can prescribe them. [7]

Prescribing treatment for oliguria should be based on the following important rules:

1. If the diagnostic results show a normal fluid content in the body tissues (no dehydration), the patient is given diuretics for several days. It is important not to overdose and not to use diuretics for too long to avoid increased potassium excretion and heart rhythm disturbances.
2. Hormones (testosterone) optimize protein metabolism and renew kidney tissue.
3. In severe intoxication, glucose solution and calcium preparations are administered.
4. Antibiotics are prescribed only in inflammatory etiology of oliguria, but the dosage should be deliberately lower, which is associated with slow excretion of drugs from the body.
5. Oliguria associated with heavy metal intoxication is treated with the use of antidotes - in particular, unitiol. In addition, measures to accelerate the elimination of toxins from the body.
6. If the cause of oliguria was urolithiasis, then use a comprehensive treatment with the use of drugs that normalize the acid-base state of the urine. It is possible to perform ultrasound stone crushing, or surgical intervention.
7. If oliguria is the result of shock, the first thing to do is to eliminate the trigger mechanism - for example, neutralize the infection, compensate for blood loss, etc. Additionally, large volumes of plasma replacement fluids are administered. If necessary, anti-allergic treatment is prescribed.
8. In case of mechanical obstruction to normal urine output, catheterization, bladder puncture, etc. Are performed.
9. For a mild diuretic effect and activation of metabolic processes can be used blood thinners (eg, Pentoxifylline).
10. In severe failure of renal function, the use of a dialysis machine is appropriate.

Medications

If necessary, antibiotics are prescribed (for example, if oliguria is due to pyelonephritis), taking into account the reaction of the urine, the degree of nephrotoxicity of the drug, belonging and resistance of the infectious agent. For example, with an alkaline urine reaction, macrolides and aminoglycosides are more often prescribed, with weakly acidic - nitrofuran drugs, ampicillin. More universal in this aspect are antibiotics of tetracycline, cephalosporin series, as well as levomycetin.

Diuretics are often prescribed - in particular, Furosemide (Lasix) orally, as well as in the form of intravenous or intravenous injections.

In the category of anti-inflammatory drugs may be prescribed proteolysis inhibitors - for example, aminocaproic acid 1 g up to six times a day, or Contrical once a day 10-20 thousand units in the form of intravenous drip infusion with saline.

To normalize cellular and capillary permeability it is recommended to use vitamin C in the form of intramuscular injections of 5 ml of 5% solution up to three times a day. Pentoxifylline (Trental) is prescribed to optimize microregulatory processes.

Often taken antispasmodics and analgesics:

• Papaverine is administered intramuscularly by 0.5-2 ml of 2% solution. The duration of treatment is determined by the doctor. Possible side effects: visual disturbances, dry mucous membranes, weakness, headache.
• No-shpa is taken orally 1 tablet three times a day (unless otherwise prescribed by the doctor). Possible side effects: tachycardia, weakness, constipation, dizziness.
• Baralgin is taken 1 tablet 2-3 times a day. The duration of administration for more than five consecutive days is not recommended. During administration it is necessary to monitor blood pressure (hypotension is possible).

Some patients are treated with biogenic stimulants, which have stimulating properties and accelerate the recovery processes in the body:

• Aloe extract is injected subcutaneously daily 1 ml (1 ampoule). Duration of therapy - 10-30 days. The drug is usually well tolerated, sometimes there may be soreness at the injection site.
• Apilac in the form of sublingual tablets take 1 tablet three times a day. The tablet is held under the tongue until it is completely absorbed. The drug may cause allergic reactions and sleep disorders.

Vitamin preparations (A, B group), phytotherapy, physiotherapy (electrophoresis with potassium iodide, phonophoresis, microwave therapy) are prescribed. [8]

Prevention

It is quite possible to prevent oliguria and its complications. To do this, it is enough to follow these accessible rules:

• treat any inflammatory pathologies in a timely manner;
• See your doctor regularly for checkups for preventive care;
• avoid hypothermia of the lumbar region and the body as a whole;
• eliminate alcohol;
• eat a good quality diet, avoiding starvation and overeating;
• minimize the use of spices, seasonings, hot sauces, salt, fatty broths;
• keep a balance of fats, proteins and carbohydrates in the diet;
• Drink enough fluids throughout the day;
• not to forget the need for physical activity;
• comply with sanitary and hygienic rules.

Forecast

Prognostic information depends on the cause of pathology, on the timeliness of seeking medical help, on the general condition of the patient's body.

Lack of treatment or inadequate therapy (self-treatment) can cause complete blockage of urine output (anuria), which is considered a life-threatening condition.

Uncontrolled use of diuretics in oliguria can lead to the development of acute renal failure, a serious condition that can also end very unfavorably for the patient. [9]

Extended oliguria can cause irreversible consequences in the urinary system and, in particular, in the kidneys. Such changes will not be restored to normal even after full treatment. In severe cases, hemodialysis and kidney transplantation are necessary.