Urinalysis and Body Fluids Review

Many urine samples may contain:
- Just a rare epithelial cell.
Small amounts of constituents may be:
- Normal or pathogenic depending on the clinical context.
Some constituents can be easily distorted.

Characteristics of RBCs in urine:
- Smooth, non-nucleated, biconcave disks.
- Crenated appearance in hypersthenuric urine.
- Ghost cells can be seen in hyposthenuric urine.
Identification methods:
- Use high power microscopy.

Carry the microscope with two hands, supporting the base with one hand.
Always maintain the microscope in a vertical position.
Clean optical surfaces only with high-quality lens tissue and commercial lens cleaner.
Do not use the 10x and 40x objectives with oil.
Clean the oil immersion lens post-use.
Always remove slides with the low-power objective raised.
Store the microscope with the low-power objective in position and the stage centered.

Phase-Contrast Microscopy:
- Increases the refractive index of:
- Casts
- Mucus threads
- Trichomonas
Polarizing Microscopy:
- Used for:
- Crystals
- Lipids
- Ability to split light into two beams, showing multicolored crystals.
- Example: Cholesterol produces Maltese cross formations.
Interference-Contrast Microscopy:
- Produces three-dimensional images.

Lipid Stains:
- Oil Red O and Sudan III are used to stain triglycerides and neutral fats.
- Cholesterol does not stain but polarizes under polarized light, showing a Maltese cross pattern.
Gram Stain:
- Used for identification of bacterial casts.
Hansel Stain:
- Effective for urinary eosinophils.
- Uses methylene blue and eosin Y, which are reported to be better than Wright stain.
Prussian Blue Stain:
- Visualizes hemosiderin granules seen with hemoglobinuria.

Bright Field Microscopy:
- Most common in urinalysis.
- Requires reduced light for optimal viewing.
- Magnification settings are typically at 10x and 40x.
- Par focal characteristic allows minimal adjustments when changing objectives (use fine adjustment).
- Light reduction utilizing the rheostat is important.
- Condenser can be adjusted up and down for focusing.
- Avoid the use of the aperture diaphragm.

A consistent reporting system within the laboratory is necessary, including:
- Terms like rare, few, moderate, many, or 1+, etc. (semiquantitative measures).
- For casts: average number per low power field (Ipf).
- For RBCs and WBCs: average number per high power field (hpf).
- Reporting for epithelial cells, crystals, etc., should also be done semiquantitatively.

Ensure consistency in examination:
- Minimum of 10 low power fields (Ipfs) and 10 high power fields (hpfs).
Low power examination:
- Identifies casts and general composition; check edges for casts using the glass slide method.
High power examination:
- Identification of specific elements.
Initial focusing should start with low power and reduced light:
- Focus on epithelial cells while ignoring artifacts in differing planes.
- Use continuous fine adjustment for the best view.

Large pollen grains can lead to interference:
- May appear with no usual sediment elements in view.
- Pollen grains exist in a different liquid plane than urine constituents due to their larger size.

Collect 0.5-1.0 mL of sediment after decantation:
- Concentration factor can be calculated as volume of urine centrifuged divided by sediment volume.
- This affects the probability of detecting low quantities of formed elements.
Usage of aspirating instead of pouring off urine is recommended (e.g., pipettes).
Gently mix sediment, ensuring not to be vigorous.

Maintain consistency in the volume examined:
- Commercial systems often control this volume.
- For glass slide methods, the volume should be around 20 μL with a 22 x 22 glass cover slip.
- Ensure cover slip does not overflow;
- Heavier elements, such as casts, will flow outside.