Synovial fluid - ch12 objectives

Describe the formation and function of synovial

fluid

Formation - Synovial fluid is produced as an ultrafiltrate of blood plasma, Clear, viscous and primarily composed of hyaluronan, lubricin, proteinase, collagenases, and prostaglandins.

Function - Moistens and lubricates joints, Provides nutrients to articular cartilage

Relate laboratory test results to the four common classifications of joint disorders.

• Noninflammatory

  • WBCs<1000, clear, yellow liquid, good viscosity, neutrophils <30%

  • similar to blood glucose

• Inflammatory

  • Immunologic - cloudy, yellow fluid, poor viscosity, WBCs 2,000-75,000,

  • Crytsal induced- cloudy or milky, low viscosity, WCS 100,000, Neutrophils <70%, decreased glucose level

• Septic

  • Cloudy, yellow-green fluid, WBCs 50,000 to 100,000, Neutrophils>75%, positive culutre and graim stain

• Hemorrhagic

  • Cloudy, red fluid, WBCs and neutrophils equal to blood,

  • normal glucose level

State the five diagnostic tests performed most routinely on synovial fluid.

1. Cell counts/Differential

2. Crystal Identification/Analysis

3. Chemistry Tests

4. Microbial Tests

5. Serological Tests

Determine the appropriate collection tubes for requested laboratory tests on synovial fluid.

• Tube 1: The first 4 to 5 mL of the synovial fluid

  • plain, nonanticoagulated red stopper tube and observed for clotting

• Tube 2: The next 4 to 5 mL

  • sodium heparin (green stopper) or EDTA tube (lavender stopper) tube • Used for cell count, differential count, and crystal identification.

• Tube 3: The last 4 to 5 mL

  • sterile tube with heparin (green stopper) or sodium polyanethol sulfonate (yellow stopper) tube, Used for microbiological studies

Describe the appearance of synovial fluid in normal and abnormal states.

Normal - 4-6 cm long before breaking, solid ropey mass, colorless and clear

Abnormal - Low viscosity, no clot friable clot, Rice bodies, Ochronotic shards=blackpeper

Discuss the normal and abnormal cellular composition of synovial fluid.

Abnormal: LE (Lupus erythematosus) Cells: neutrophils that have engulfed a nucleus of a lymphocyte that has been altered by an

antinuclear antibody

• Reiter Cell: macrophage containing ingested nuclei of a  neutrophil commonly found in most inflammatory synovial fluids

• RA Cell: isn't a single distinct cell type, but rather refers to neutrophils, which are the predominant inflammatory cells found in rheumatoid arthritis (RA) synovial fluid

List and describe six crystals found in synovial fluid.

• Monosodium Urate Crystals – Gout

• Calcium Pyrophosphate dehydrate crystals (CPPD) - pseudogout

• Cholesterol crystals: colorful

• Corticosteroid crystals

• Calcium Oxalate - Renal dialysis

• Apatite crystals - calcified cartilage degeneration 

Explain the differentiation of monosodium urate and calcium pyrophosphate crystals using polarized and compensated polarized light.

MSU needle shaped and CPPD not needle shaped when viewed correctly on axis

State the clinical significance of glucose and lactate tests on synovial fluid.

Glucose - Normal levels are based on blood glucose level, shouldn't be lower than 10mg/dl

Lactate - Levels greater than 9mmol/L (81mg/dL) indicate bacterial arthritis, increased in septic arthritis

List four genera of bacteria found most frequently in synovial fluid.

• Staphylococcus

• Streptococcus

• Haemophilus

• N. gonorrhoeae

Describe the relationship of serological serum testing to joint disorders.

Due to the association of the immune system with the inflammation process, serological testing plays an important role in the diagnosis of joint disorders. Most of these tests are performed on serum, synovial fluid is a confirmatory measure.

RA and Systemic lupus erythematous - Diagnosed in the serology laboratory by presence autoantibodies in the patient’s serum.

Lyme disease - Detection of antibodies to the causative agent B. burgdorferi in the patient’s serum confirms the cause of the arthritis