Urinary syndrome in urinalysis

Role of urinalysis in diagnosis

The routine urinalysis (UA) serves as the baseline and primary step in laboratory diagnostics for any pathology of the urinary system. Its main goal is to rule out urinary tract infections (UTIs) and various forms of nephropathies. It is the urinalysis that allows the detection of urinary syndrome, changes in which often precede the appearance of a full-blown clinical picture of the disease.

Specialized laboratory and instrumental methods merely complement these general clinical data, allowing for the following tasks:

• Detection of latent forms of kidney disease.
• Assessment of the activity degree of the current pathological process.
• Anatomical assessment of the kidneys (studying their size, shape, presence of asymmetry, detecting cysts and tumors).
• Assessment of renal blood flow.
• Clarification of the functional capacity of renal tissue.

Structure and components of urinary syndrome

Traditionally, laboratory manifestations are divided into two groups depending on their clinical significance.

Main components:

• Proteinuria (presence of protein in the urine).
• Hematuria (presence of red blood cells).

These signs can either combine with each other or manifest in isolation, when one symptom clearly predominates over the other.

Additional components:

• Leukocyturia.
• Cylindruria.

In a narrow nomenclature sense, urinary syndrome is considered an independent nosological entity. In this context, it is defined exclusively as asymptomatic proteinuria and hematuria. This fundamentally distinguishes it from other nephrological syndromes, in which laboratory shifts are accompanied by a full-blown clinical picture: pronounced edema, arterial hypertension, and oliguria.

Physical properties of urine

In addition to sediment microscopy and biochemical composition assessment, evaluating the physical (general) and physicochemical properties of urine plays a crucial role. Basic parameters include:

1. Quantity (daily diuresis).
2. Urine color.
3. Transparency.
4. Relative density (specific gravity).
5. Reaction (pH).

Shifts in these specific parameters are of colossal diagnostic significance and often act as harbingers of serious disorders. The only exception to the rule of the "asymptomatic" course of urinary syndrome is gross hematuria. In this condition, a sharp and visible-to-the-naked-eye change in color occurs, which immediately draws attention.

Transient changes in infections and fever

When interpreting urinalysis results, it is critically important to consider the presence of acute respiratory viral infections (ARVI) and concomitant intoxication.

• In uncomplicated ARVI courses, pathological changes in the urine are absent.
• In pronounced fever and severe intoxication syndrome, transient changes may occur.

Such deviations include: an increase in the relative density of urine, mild leukocyturia, proteinuria and cylindruria, as well as possible bacteriuria, glucosuria, and hematuria. The main feature of these shifts is their benign nature: they independently and completely disappear as soon as body temperature normalizes and intoxication is fully resolved.

Biochemical monitoring in moderate-to-severe conditions

If the underlying disease becomes moderate or severe, a single urinalysis is no longer sufficient. In such cases, a blood chemistry panel (BCP) is indicated.

Its goal is to assess the presence and degree of internal organ dysfunction, as well as to identify complications and concurrent pathologies. The mandatory list of parameters includes:

• Enzymes: ALT, AST, amylase.
• Metabolites: urea.
• Electrolytes: sodium, potassium, total calcium, total magnesium, inorganic phosphorus, chlorides.

Class and exam questions

What else to study on this topic

• Anatomical assessment of the kidneys: methods for detecting cysts, tumors, and asymmetry.
• Assessment of renal blood flow and functional capacity of the kidneys.
• Differential diagnosis of transient and true proteinuria.
• The role of urinary enzymes: urokinase and transamidase.

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.