Microscopic Examination of Urine

Recommended urine volume for sediment prep

10-15 mL (recommended: <12 mL)

Centrifuge speed and time for urine sediment prep

400 RCF for 5 minutes

How much urine should remain after centrifugation?

0.5-1.0 mL

Sediment volume transferred to slide and coverslip size

20 µL sediment, 22 x 22 mm coverslip

Microscope magnification for urine sediment exam

10 LPO, 10 HPO under reduced light

If <12 mL urine is available

Centrifuge 3 mL

If <3 mL urine is available

Examine sediment without centrifugation

Formula for calculating RCF

RCF = 1.118 x 10⁻⁵ x radius in cm x RPM²

Objective used first to detect casts

LPO (Low Power Objective)

Objective used for further identification

HPO (High Power Objective)

Purpose of Addis Count

Quantitative measure of formed elements using hemacytometer

Addis Count specimen and preservative

12-hour urine specimen; preservative: formalin

Normal Addis Count for RBCs

0-500,000/12-hr urine

Normal Addis Count for WBCs & ECs

0-1,800,000/12-hr urine

Normal Addis Count for hyaline casts

0-5,000/12-hr urine

Location of first lens system

Objective, adjusted near specimen

Location of second lens system

Eyepiece (ocular lens)

What does resolution mean?

Ability to distinguish two small objects apart

Meaning of parfocal

Minimal adjustment needed when switching objectives

Purpose of camel-hair brush

Remove dust from optical surface

Purpose of lens paper

Clean optical surfaces of microscope

Purpose of commercial lens cleaner

Remove contaminants on lens

How to remove oil on lens

Lens paper, then lens paper moistened with cleaner

Why avoid xylene for oil lenses

Xylene is toxic