Structure of general urinalysis parameters
To ensure that the parameters are within the normal range, the clinical analysis is traditionally evaluated across three main sections. Any significant deviation in these groups indicates the development of a pathological process.
- Physical (general) properties. This group includes the volume of excreted fluid (daily diuresis), its color, and degree of transparency. Relative density (specific gravity) and medium reaction (pH) are also evaluated obligatorily.
- Chemical parameters. Detection and evaluation of the concentration of substances such as protein, glucose, ketone bodies, bilirubin, urobilinogen, and nitrites.
- Sediment microscopy. The specialist examines the sediment for cellular and non-cellular elements. The focus is on erythrocytes, leukocytes, epithelial cells, casts, salt crystals, as well as bacteria and yeast cells.
Diagnostic significance and urinary syndrome
Deviations in physical properties and sediment composition are of immense diagnostic value. They form the basis of the concept of urinary syndrome — a condition characterized by the asymptomatic appearance of protein (proteinuria) and erythrocytes (hematuria) in the excreted fluid.
Most often, this syndrome is latent, causing no discomfort to the patient, and remains the sole marker of kidney damage for a long time. The only exception is macrohematuria, in which the color of the fluid changes abruptly and visibly, immediately drawing attention.
From the perspective of general renal pathology, all compositional changes are divided into two categories:
- Quantitative shifts in normal components. These are significant parameter fluctuations extending beyond normal limits (e.g., excessive protein excretion or a sharp change in specific gravity).
- Appearance of pathological components. The emergence of elements that should not be present in excessive amounts in a healthy body (bacteria, casts, glucose, ketones, clumps of erythrocytes and leukocytes).
Main components of urinary syndrome
Key pathological changes detected during the study are classified according to several mechanisms and severity degrees.
| Component | Detailed characteristics and classification |
|---|---|
| Proteinuria | By severity: moderate (subnephrotic, up to 1–3 g/day) and massive (nephrotic, greater than 3–3.5 g/day). By mechanism: prerenal (in paraproteinemias), renal, and postrenal (due to urinary tract inflammation). |
| Hematuria | Divided into micro- and macrohematuria. By origin, it is glomerular (dysmorphic, altered cells, often with proteinuria) and urological (unchanged, "fresh" cells against the background of trauma, tumors, or stones). |
| Leukocyturia | Can be neutrophilic (indicating a bacterial infection, such as pyelonephritis) or abacterial lymphocytic (indicating immune glomerular inflammation). |
| Cylindruria | Various casts may be found in the sediment: erythrocyte casts (marker of glomerular bleeding), leukocyte casts, granular casts, hemoglobin casts, or mixed casts. |
Renal proteinuria is worthy of separate note. It is subdivided into glomerular, which arises due to increased permeability of the glomerular basement membrane, and tubular, associated with impaired reabsorption of low-molecular-weight proteins in the proximal tubules.
Classification of nephrological syndromes
Depending on the predominant changes in laboratory tests and the clinical picture, the following main nephrological syndromes are distinguished:
- Isolated urinary syndrome.
- Nephrotic and nephritic (acute nephritic) syndromes.
- Hypertensive syndrome.
- Acute kidney injury (AKI) and chronic kidney disease (CKD).
- Tubulointerstitial disorders (tubular dysfunction).
- Urinary tract obstruction syndrome (most often belongs to urological practice).
To easily remember the mechanisms of proteinuria, trace the pathway of urine formation: "before the kidney" — prerenal (problem in the blood), "in the kidney" — renal (glomeruli and tubules), "after the kidney" — postrenal (pathway inflammation).
Class and exam questions
How to distinguish glomerular hematuria from urological hematuria based on test results?
In glomerular origin, altered (dysmorphic) erythrocytes are visible in the sediment, often accompanied by proteinuria and erythrocyte casts. Urological hematuria (characteristic of stones or trauma) is distinguished by the presence of "fresh", unchanged erythrocytes.
What does the appearance of abacterial lymphocytic leukocyturia mean?
Unlike neutrophilic leukocyturia, which points to a bacterial infection (e.g., pyelonephritis), the lymphocytic type without bacteria indicates an immune inflammatory process in the renal glomeruli.
What constitutes the latency of urinary syndrome?
Urinary syndrome manifests as isolated proteinuria and hematuria without any external symptoms. The patient feels healthy, which is why the pathology is only detected during a laboratory test.
What else to study on this topic
- Evaluation of physical properties and cerebrospinal fluid (CSF) microscopy.
- Specific urine enzymes: diagnostic role of urokinase and transamidase.
- Acute kidney injury (AKI) and chronic kidney disease (CKD).
- Tubulointerstitial disorders and tubular dysfunction syndromes.
- Clinical and laboratory differences between nephritic and nephrotic syndromes.
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