Hypostenuria : Causes, Symptoms, Diagnosis & Treatment

• Causes Of Hypostenuria
• Physiological Causes
• Kidney Disease
• Diabetes Insipidus
• Diagnostics
• Correction
• Forecast

Hypostenuria is a pathological condition characterized by a decrease in the relative density of urine less than 1005 g / ml. A decrease in the specific gravity of urine indicates a violation of the concentration function of the kidneys, which occurs with various nephrological diseases, diabetes insipidus, etc. With hypostenuria, urine has a less intense color, sometimes it can be completely transparent. Relative density is examined in the general analysis of urine. Correction of this laboratory deviation is carried out by treating the underlying disease.

Causes of hypostenuria

Physiological causes

During the day, the relative density of the urine of a healthy person varies widely - from 1003 to 103 g / ml. This indicator depends on many factors, for example, with excessive fluid intake, the specific gravity may decrease for a short time. The kidneys of newborns are not able to concentrate urine, so they have hypostenuria (about 1002 g / ml).

Also, physiological hypostenuria can be considered therapy for edematous syndrome with diuretics, since the relative density is inversely proportional to the volume of urine excreted. During the period of convergence of edema under the influence of diuretic drugs, diuresis increases and dilution of urine occurs.

kidney disease

The most common cause of hypostenuria is kidney disease. To maintain the ion balance in the blood and other tissues of the body during urination, the tubules of the kidneys excrete various electrolytes into the urine (sodium, potassium, calcium, chlorides, bicarbonates, etc.). This is called "the concentration function of the kidneys." If the tubules are damaged, this ability is impaired.

Since tubular damage is observed to some extent in almost every renal disease, they are often accompanied by hypostenuria. Its severity directly correlates with the severity of nephrological pathology. Specific treatment leads to a gradual normalization of the specific gravity. The most common kidney diseases in which hypostenuria is observed:

• glomerulonephritis;
• pyelonephritis;
• hypertensive nephropathy;
• tubular dysfunction (tubulointerstitial nephritis, renal tubular acidosis);
• chronic renal failure.

Hypostenuria

diabetes insipidus

Vasopressin (antidiuretic hormone) is the main regulator of water balance in the body. With diabetes insipidus, its absolute (in the central form) or relative (in the nephrogenic form) insufficiency occurs, due to which severe polyuria develops (up to 15-2 liters per day) and hypostenuria due to urine dilution.

Replacement therapy of central diabetes insipidus quickly leads to an increase in relative density to normal values. The nephrogenic form, due to the resistance of the renal tubules to antidiuretic hormone, is much more difficult to treat, so hypostenuria can persist for a long time.

Causes of central NSD:

• brain injury;
• surgical interventions on the central nervous system;
• brain tumors;
• transferred meningitis or encephalitis.

Causes of nephrogenic NSD:

• mutations in vasopressin receptors;
• various pathologies of the kidneys;
• electrolyte disturbances (hypercalcemia, hypokalemia).

Diagnostics

Despite the fact that this condition may have physiological causes, if hypostenuria is detected, you should immediately contact a general practitioner or nephrologist to determine the etiological factor. At the appointment, the doctor asks the patient about complaints that may be useful in differential diagnosis, such as nighttime urge to urinate (nocturia), which is characteristic of kidney disease, or a constant strong feeling of thirst, typical of patients with untreated diabetes insipidus.

On examination, attention is drawn to the presence of edema on the face or lower extremities. During a physical examination, blood pressure is measured, and a Pasternatsky symptom is checked. It is worth noting that test strips are used when determining relative density during a clinical urinalysis.

The reagent zone of the strip changes its sensitivity depending on the pH of the medium, therefore, with an alkaline reaction of urine, a false underestimation of the specific gravity is possible. The following studies are also assigned:

• Blood tests. In a biochemical blood test, there may be an increase in the concentration of urea, creatinine, C-reactive protein. In people suffering from diabetes insipidus, hypernatremia and an increase in plasma osmolarity are detected.
• Urinalysis. Other indicators of the general analysis of urine, such as hematuria, proteinuria, leukocyturia, can help in the diagnostic search for an etiological factor. In people with diabetes insipidus, the sodium concentration and osmolarity of urine is reduced.
• Hormonal studies. Determination of the content of antidiuretic hormone is carried out for the differential diagnosis of forms of diabetes insipidus. With central NSD, the concentration of the hormone is reduced, with nephrogenic - normal or even increased.
• Ultrasound of the kidneys. In nephrological diseases, various pathological signs are found - expansion of the pelvicalyceal system, changes in the parenchyma, a decrease in the size ("shrinkage") of the organ.

Diagnosis of hypostenuria

Correction

There are no independent methods for correcting hypostenuria. To eliminate it, treatment of the underlying disease is necessary. The following drugs are used as conservative therapy:

• Antibiotics. Patients with pyelonephritis are prescribed antibacterial agents from the group of penicillins (amoxicillin) or cephalosporins (cefexime).
• Glucocorticoids. To stop the inflammatory process in the renal tissue with glomerulonephritis, glucocorticosteroids (prednisolone, methylprednisolone) are used.
• Cytostatics. In severe and rapidly progressive forms of glomerulonephritis, in case of ineffectiveness of glucocorticoids, cytostatics (azathioprine, cyclophosphamide) are added to the treatment.
• Desmopressin . This drug is a synthetic analogue of antidiuretic hormone. In tablet or intranasal form, it is used as hormone replacement therapy for the treatment of the central form of diabetes insipidus.
• NSAIDs. They are prescribed for nephrogenic NSD. Non-steroidal anti-inflammatory drugs (indomethacin, ibuprofen) can reduce the formation of prostaglandins in the kidneys, which several times increases the sensitivity of the kidney tubules to vasopressin.
• Diuretics. Thiazide diuretics with long-term use reduce the excretion of water in the urine. Due to this property, they are successfully used in patients with NSD. To enhance the implementation of this effect, the patient should limit the intake of table salt.

Forecast

Hypostenuria may indicate excessive fluid intake, as well as be a sign of severe nephrological or endocrine pathology. In any case, its appearance requires a visit to the doctor. The prognosis is determined by the underlying disease, the timeliness of diagnosis and the literacy of the treatment.