CLINICAL MICROSCOPY - Must to Know

Nephron

Basic structural unit of kidney

1M/kidney

Urethra

F: 3-4 cm

M: 20 cm

Urine formation (order)

Glomerulus 🡪 Bowman's capsule 🡪 PCT 🡪 Loop of Henle 🡪 DCT 🡪 CD

PCT

65% of reabsorption

ADH

Regulate H2O reabsorption in DCT and CD

Urine composition

95-97% H2O

3-5% solids

60g

TS in 24 hrs

35g: Organic = Urea (major)

25g: Inorganic = Cl (#1) > Na+ > K+

Clearance tests

Evaluate glomerular filtration

1. Urea clearance

2. Creatinine clearance = most common

3. Inulin clearance = gold standard

4. Beta2-microglobulin

5. Radioisotopes

Creatinine clearance

Formula:

Cc = U x V x 1.73

P A

Normal values:

M = 107-139 mL/min

F = 87-107 mL/min

Tubular Reabsorption

1st function to be affected in renal disease

Concentration tests

Evaluate tubular reabsorption

Fishberg test (Old)

Patient is deprived of fluid for 24hrs then measure urine SG

(SG ≥ 1.026)

Mosenthal test (Old)

Compare day and night urine in terms of volume and SG

Specific Gravity (New)

Influenced by # and density of particles in a solution

Osmolarity

Influenced by # of particles in a solution

Principle: Freezing point depression

- 1 Osm or 1000 mOsm/kg of H2O will lower the FP of H2O (0'C) by 1.86'C - 🡫FP = 🡩Osm

Example:

Determine Osm in mOsm/kg

Temp. = -0.90'C

Solution:

1000 mOsm/kg = _ _x____

-1.86'C -0.90'C

x = 484 mOsm/kg

PAH test

p-aminohippuric acid

PSP test

Phensulfonphthalein test

Obsolete, results are hard to interpret

Midstream/Catheterized

Urine culture

Suprapubic aspiration

Anaerobic urine culture

3 glass technique

For detection of prostatic infection

1. 1st portion of voided urine

2. Middle portion of voided urine: Serves as control for kidney and bladder infection

-If (+), result for #3 is considered invalid

3. Urine after prostatic massage

Compare WBC and Bacteria of specimen 1 and 3

Prostatic infection: 1 < 3 (10x)

Pediatric specimen

Wee bag

Drug Specimen Collection

Chain of custody: step by step documentation of handling and testing of legal specimen

Required amount: 30-45 mL

Temperature (urine): 32.5-35.7'C (w/in 4 mins)

Blueing agent 🡪 Toilet bowl (to prevent adulteration)

Occasional/Single/Random

Routine

Qualitative UA

24 hr

1st voided urine 🡪 discarded

w/ preservative

Ex. 8AM 🡪 8AM

12 hr

Ex. 8AM 🡪 8PM

Addis count: measure of formed elements in the urine using hemacytometer

Afternoon (2PM-4PM)

Urobilinogen (alkaline tide)

4 hr

Nitrite determination (1st morning/4 hr)

NO3 🡪 NO2 = (+) UTI

1st morning

Pregnancy test (hCG)

Ideal specimen for routine UA

Most concentrated and most acidic = preservation of cells and casts

Fasting/2nd morning

Glucose determination

2nd voided urine after a period of fasting

Clarity

Bacterial multiplication

Precipitation of AU/AP

Glucose

Glycolysis

Ketones

Volatilization

Bilirubin

Photooxidation

Urobilinogen

Oxidized to urobilin

RBC/WBC

Disintegrate in alkaline urine

pH

Urea ---(Urease)---> NH3

Bacteria

Multiplication

Odor

Urea ---(Urease)---> NH3

Nitrite

Bacterial multiplication

Refrigeration

2-8'C

🡩 SG (hydrometer/urinometer)

Precipitate AU/AP

Formalin

Addis count

Boric acid

Urine culture

Bacteriostatic to contaminants

Sodium fluoride

Glucose

Sodium benzoate/

Benzoic acid

Substitute for sodium fluoride

Saccomanno's fixative

50% ethanol + carbowax

Cytology (50mL urine)

Volume

NV:

24 hr = 600-1200 mL

Ave (24 hr) = 1200-1500 mL

Night: Day ratio = 1:2 to 1:3

Routine UA

Vol = 10-15 mL (Ave: 12 mL)

-15 mL: for urinometry

-physical, chemical, microscopic exam

Polyuria

🡩 Urine volume

-Diabetes Mellitus: 🡩 vol, 🡩 SG

-Diabetes Insipidus: 🡩 vol, 🡫 SG

Oliguria

Calculus/kidney tumors

Dehydration

Anuria

Complete cessation of urine flow

Nocturia

>500mL w/ SG <1.018

Pregnancy

Urine color

Roughly indicates the degree of hydration

Should correlate w/ urine SG

🡫 fluid intake: Dark urine, 🡩 SG

Urine pigments

1. Urochrome

-Major pigment (yellow)

-Production is directly proportional to metabolic rate

-🡩 in thyrotoxicosis, fever, starvation

2. Uroerythrin

-Pink pigment

-May deposit in amorphous urates and uric acid crystals

3. Urobilin

-Dark yellow/orange

-Imparts an orange-brown color to a urine w/c is not fresh

Normal

Colorless to deep yellow

Abnormal

Red/red brown (most common)

Colorless/Pale yellow

Polyuria: DM/DI

Amber

Bilirubin (yellow foam)

[Protein: white foam, concentrated urine]

Orange

Pyridium (Tx: UTI)

-Yellow/orange foam

-Orange and viscous

Yellow-green

Yellow-brown

Bilirubin ---(oxidized)---> Biliverdin

Green

Pseudomonas aeruginosa

Blue-green

Clorets, methylene blue, phenol

Indican (blue): Hartnup disease or Blue diaper syndrome

Cloudy/Smoky red

Hematuria (intact RBCs)

Clear red

Hemoglobin, Myoglobin

Red/Purple/Burgundy red/ purplish red/Portwine

Porphyria

(Lead poisoning: normal color)

Brown/black

Methemoglobin (acid urine)

Homogentisic acid: Alkaptonuria

-Urine darkens after a period of standing

-(-) Homogentisic acid oxidase

Cola-colored

Levodopa (Tx: Parkinsonism)

Red 🡪 Brown (alkaline)

Yellow

Mepacrine/Atabrine (Tx: Malaria, Giardiasis)

Red to brown

Metronidazole/Flagyl (Tx: Trichomoniasis, Amoebiasis, Giardiasis) Methyldopa/Aldomet (Antihypertensive)

Orange-red (acid)

Phenazopyridine/pyridium (Tx: UTI)

Bright orange-red (acid)

Rifampin (Tx: TB) = all body fluids are red

Bright yellow

Riboflavin (Multivitamins)

Nubecula

Faint cloud in urine after a period of standing

WBCs, epithelial cells and mucus

Bilifuscin (Dipyrrole)

Hemoglobin Köln = unstable

Red-brown urine

Clear

Transparent, no visible particulates

Hazy

Few particulates, print easily seen through urine

Cloudy

Many particulates, print blurred through urine

Turbid

Print cannot be seen through urine

Milky

May precipitate or clot

Bacteria

Uniform turbidity NOT cleared by acidification or filtration

Chyluria

Lymph fluid in urine

Filariasis

Squamous epithelial cells

🡩 females

Radiographic contrast

media

🡩 SG by refractometer (>1.040)

Rgt strip: not affected by RCM

Vaginal cream

Tx: Candida

Pseudochyluria

Acidic urine

AU

RCM

Alkaline urine

AP

Carbonates

Soluble w/ heat

AU

Uric acid

Soluble w/ dilute acetic acid

RBCs

AP

Carbonates

Insoluble in dilute acetic acid

WBCs

Yeasts

Spermatozoa

Bacteria

Soluble in ether

Lipids

Lymph fluid

Chyle

SG

Density of solution compared w/ density of similar volume of distilled H2O at a similar temperature

NV = 1.003-1.035 (random)

SG <1.003 = not a urine except DI

Refractometer (TS meter)

Based on refractive index:

RI = _light velocity in air_

light velocity in soln

Compensated to temperature (15-38'C)

Corrections:

a. 1g/dL glucose: (-0.004)

b. 1g/dL protein: (-0.003)

Calibrations:

a. Distilled H2O = 1.000

b. 5% NaCl = 1.022 ± 0.001

c. 9% Sucrose = 1.034 ± 0.001

Urinometer

Requires temperature correction

a. 🡩 3'C calibration temperature (20'C) = (+0.001)

b. 🡫 3'C calibration temperature (20'C) = (-0.001)

Requires correction for glucose and protein (Rf/U)

Rf < U by 0.002

Refractometer reading is lower than the urinometer reading by 0.002

Urinometer calibration

K2SO4 solution: 1L H2O + 20.29g K2SO4

SG = 1.015

Isosthenuria

SG = 1.010 (Glomerular filtrate)

Hyposthenuria

SG < 1.010

Hypersthenuria

SG > 1.010

Aromatic/Odorless

Normal

Ammoniacal

Urea ---(Urease)---> NH3

Ex. UTI (Proteus: 🡩 urease)

Fruity, sweet

DM (Ketones)