SYNOVIAL FLUID - LEC

TUBE COLLECTION

heparin or EDTA for cell counts

TUBE COLLECTION FOR OTHER TESTS

nonanticoagulated tube

for glucose analysis

NaF tube

Cell Counts

• TOTAL LEUKOCYTE COUNT

• SELDON RBC COUNT

• VISCOUS FLUID

• COUNT SAME MANNER AS CSF

• DILUTING FLUID: NORMAL SALINE (0.3%)

• METHYLENE BLUE: STAIN WBC NUCLEI

• DIFFERENTIAL COUNT: SAME WITH CSF

Viscous fluid

pretreat with a pinch of hyaluronidase to 0.5 mL of fluid or

one drop of 0.05% hyaluronidase in phosphate buffer per mL of fluid 🡪37ºC

for 5 minutes.

VOLUME

<3.5ML

COLOR

COLORLESS TO PALE YELLOW

CLARITY

CLEAR

VISCOSITY

ABLE TO FORM 4-6 CM LONG

LEUKOCYTE COUNT

<200 CELLS/UL

NEUTROPHILS

<25% OF THE DIFFERENTIAL

CRYSTALS

NONE PRESENT

GLUCOSE: PLASMA DIFFERENCE

<10 MG/DL LOWER THAN THE BLOOD GLUCOSE

TOTAL PROTEIN

<3 G/DL

NONINFLAMMATORY

Clear, yellow fluid

Good viscosity

WBCs <1000 μL

Neutrophils <30%

Normal glucose (similar to blood glucose)

Inflammatory

A. immunologic origin

Cloudy, yellow fluid

Poor viscosity

WBCs 2000–75,000 μL

Neutrophils >50%

Decreased glucose level

Possible autoantibodies present

Inflammatory

B. crystal-induced origin

Cloudy or milky fluid

Low viscosity

WBCs up to 100,000 μL

Neutrophils <70%

Decreased glucose level

Crystals present

Septic

Cloudy, yellow-green fluid

Variable viscosity

WBCs 50,000–100,000 μL

Neutrophils >75%

Decreased glucose level

Positive culture and Gram stain

Hemorrhagic

Cloudy, red fluid

Low viscosity

WBCs equal to blood

Neutrophils equal to blood

Normal glucose level

Synovial lining cell

Similar to macrophage, but may be

multinucleated, resembling a mesothelial cell

NORMAL

LE cell

Neutrophil containing characteristic ingested: “round body”

LUPUS ERYTHEMATOUS

Reiter cell

Vacuolated macrophage with ingested neutrophils

Reiter syndrome

Nonspecific inflammation

RA cell (ragocyte)

Neutrophil with dark cytoplasmic granules containing immune complexes

Rheumatoid arthritis

Immunologic

inflammation

Crystal: Monosodium urate

SHAPE: Needle

SIGNIFICANCE: Gout

Crystal: Calcium pyrophosphate

SHAPE: Rhombic square, rods

SIGNIFICANCE: Psuedogout

Crystal: Cholesterol

SHAPE: Notched, rhombic plates

SIGNIFICANCE: Extracellular

Crystal: Corticosteroid

SHAPE: Flat, variable-shaped plates

SIGNIFICANCE: Injection

Crystal: Calcium oxalate

SHAPE: Envelop

SIGNIFICANCE: Renal dialysis

Crystal: Apatite (Ca phosphate)

SHAPE: Small particles Require electron microscopy

SIGNIFICANCE: Osteoarthritis

Glucose

Plasma-synovial fluid glucose difference = within 10mg/dL

Decreased in various joint diseases (Bacterial infection)

Protein

<3g/dL

Increased in inflammatory (RA, crystal synovitis) & septic arthritis

Uric Acid

Establishes the presence of gout

Elevated result should correlate with serum uric acid

Lactate Test

Provides rapid differentiation between inflammatory and septic arthritic