SYNOVIAL FLUID

2.  Ultra filtrate of plasma across synovial membrane
› Excludes proteins of high molecular weight
 Synoviocytes
› Secrete mucopolysaccharide which contains:
› Hyaluronic acid
› Protein
› Contains slippery proteoglycans secreted by
fibroblasts

3. 1. Reduce friction between bones
2. Lubricates joints
3. Fluid provides nutrients to cartilage
4. Lessens shock of walking and jogging impact

4. Volume <3.5 mL
Color pale yellow
Clarity clear
Viscosity forms string 4-6 cm long
Erythrocytes <2000 cells/uL
Leukocytes <200 cells/uL
Neutrophils <20% of diff.
Lymphocytes <15 % of diff.
Monocytes & macrophages 65% of diff.
Crystals NONE
Glucose <10 mg/dL (< blood glucose)
Lactate <250 mg/dL
Total protein <3 g/dL
Uric acid = blood value

5.  Method for obtaining synovial fluid by using a
needle aspiration of synovial fluid
 Volume
› Normal= 3.5 mL
› Diseased and inflamed = up to 25 mL
› Collect 2 tubes
• Heparin tube: microbiology
• Plain tube: chemistry and immunology
• EDTA (liquid): hematology

6.  synovial fluid is biochemically an ultra filtrate of
plasma, biochemistry test values are approximately
the same of serum values
 Few biochemistry tests are considered clinically
important
 Most frequently requested test is the glucose.

7.  Glucose
 Done simultaneously with blood sample (prefer 8
hour fast)
 Should be run within 1 hour of collection
 Draw in sodium fluoride – prevents glycolysis
 Difference between blood and synovial glucose
values is evaluated
 Normal = < 10 mg/dL
 Inflammatory conditions > 25 mg/dL
 Sepsis >40 mg/dL

8.  Total protein
 Not routinely performed
 Normal < 1/3 of serum value (3 g/dL)
 Large molecule, not easily filtered by membrane
 Increased protein
› Changes in membrane permeability
› Increased joint synthesis
› Indicates an inflammatory process

9.  Uric Acid
 Alone, not diagnostic
 May determine gout in conjunction with plasma uric
acid, esp. when crystals are undetectable
 Normal = serum level

11. • Lactate
1. May differentiate between inflammatory and
septic arthritis
2. Septic arthritis >250 mg/dL
3. Gonococcal arthritis = normal to low levels
4. Production results from:
• Increased demand for energy
• Tissue hypoxia
• Severe inflammatory conditions

12.  Cholesterol Crystal
 Nonspecific indications
› Associated with chronic inflammation
 Exhibit negative birefringence (compensated
polarized light)
 Usually seen extracellularly
 Polarized light: strongly birefringence
 Rhombic plates

13.  Hydroxyapatite (HA) (Calcium Phosphate) Crystals
› Associated with calcific deposition conditions
› May produce an acute inflammatory reaction
› Intracellular
› Require an electron microscope to examine
› Small, needle shaped

15.  Gram Stain
 Most infections are bacterial:
 Staphylococcus
 Streptococcus
› S. pyogenes
› S. pneumoniae
 Hemophilus
 Neisseria gonorrhea
 Fungal, viral & tubercular agents may also be
observed

16.  Cultures
 Routine culture
 Enrichment medium (chocolate agar)
 Serology:
 Autoantibody Detection (same as found in serum)
 Rheumatoid arthritis (RA)
 Lupus erythematosus (LE)

17.  Rheumatism
› A pain and stiffness of skeletal and muscular systems
 Arthritis
› All forms of rheumatism that damage articular cartilages of
synovial joints
 Osteoarthritis
› Caused by wear and tear of joint surfaces, or genetic
factors affecting collagen formation
› Generally in people over age 60

18.  Rheumatoid Arthritis
› An inflammatory condition
› Caused by infection, allergy, or autoimmune
disease
› Involves the immune system
 Gouty Arthritis
› Occurs when crystals (uric acid or calcium salts)
 Form within synovial fluid
 Due to metabolic disorders

19. Measure Normal Noninflammatory Inflammatory Septic Hemorrhagic
Volume, ml <3.5 Often >3.5 Often >3.5 Often >3.5 Usually >3.5
Clarity Transparent Transparent
Translucent-
opaque
Opaque Bloody
Color Clear Yellow Yellow to clear Yellow/green Red
Viscosity High High Low Variable Variable
WBC/mm3 <200 0-2,000 2,000-100,000
15,000-
>100,000
200-2000
% PMN <25 <25 >50 >75% 50-75
Culture Negative Negative Negative Often positive Negative