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1384 Synovial Fluid Analysis Taurine Blood Levels

Synovial Fluid Analysis
VetBooks.ir Definition Next Diagnostic Steps to Consider

necrosis of the femoral head.
Gross, physicochemical, and microscopic osteochondritis dissecans, and aseptic if Levels are Low
assessment of a sample of joint fluid ○ Neutrophils predominate in inflammatory Occasionally patients with degenerative
arthropathies (infectious, noninfectious joint disease or joint instability do not have
Physiology such as crystal induced, immune mediated). abnormalities detected in cytologic preparations.
Analysis includes assessment of viscosity, mucin Bacterial infection is usually monoarticular For polyarthropathy, multiple joints should
clot test, cell counts, protein concentration, and due to penetrating trauma. Polyarticular be sampled simultaneously to improve test
cytologic evaluation. Microscopic examination infection may be due to systemic bacte- sensitivity.
assesses cell population distribution and may rial infection, tick-borne disease, fungal
detect infectious agents. infection, viral infection, and (rarely) Specimen Collection and Handling
mycoplasmal infection. Noninfectious Fluid in EDTA (lavender top tube) for cell
Reference Interval inflammatory arthropathies typically are counts, cytologic evaluation; red top tube
Normal synovial fluid is colorless to pale polyarticular (immune-mediated diseases; (culture); refrigerate
yellow, viscous, has high mucin (hyaluronic chronic progressive polyarthritis in cats).
acid) content, and does not clot. Erythrocytes Relative Cost: $$ (Most laboratories apply
are absent. Nucleated cell counts vary among Next Diagnostic Steps to Consider lower prices for specimens from multiple joints
species and the joint sampled but are usually if Levels are High submitted at the same time.)
500/mcL (up to 3000 cells/mcL occasionally • Hemorrhage: distinguish iatrogenic versus
reported in normal joints). Synoviocytes and pathologic. Erythrophagocytosis suggests Pearls
macrophages predominate. Protein concentra- hemarthrosis. If hemarthrosis, evaluate for Some samples are very viscous, and the addition
tion ranges from 1.8-4.8 g/dL (18-48 mg/mL) trauma versus bleeding disorder. of a drop of crystalline hyaluronidase allows
by refractometer. • Degenerative arthropathy: joint radiographs, for a more accurate assessment of cell counts.
assess for joint instability/ligament tear. Addition of hyaluronidase should be done at the
Causes of Abnormally High Levels • Inflammatory arthropathy: serologic tests reference laboratory after viscosity and protein
• Increased erythrocyte count indicates iatro- and/or PCR (e.g., Borrelia spp, Ehrlichia concentration are measured and after the mucin
genic blood contamination or hemarthrosis. spp, Anaplasma spp); culture synovial fluid clot test is done and slides for cytologic evalu-
• Increased nucleated cell count occurs with (especially if monoarticular); if other disease ation are prepared.
degenerative and inflammatory arthropathies, signs present, assess for systemic disease
and may occur with neoplasia. (e.g., serum antinuclear antibody test if AUTHOR: Ruanna E. Gossett, DVM, PhD, DACVP
○ Mononuclear cells predominate in degen- proteinuria, other signs of systemic lupus EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
erative arthropathy or joint instability. erythematosus; p. 955); joint radiographs
Causes include trauma, osteoarthrosis, to assess for erosive lesions

Taurine Blood Levels

Definition Causes of Abnormally Low Levels • Plasma: 1 mL frozen heparinized plasma.
Amino acid having an important role in Dietary deficiency, poor bioavailability, excessive Spin, separate plasma immediately without
myocardial and retinal metabolism loss of metabolic precursors (cysteine), malabsorp- disturbing buffy coat and transfer plasma to
tive intestinal disease and/or familial predisposition plastic tube. Freeze immediately.
Physiology
Low blood levels of taurine have been associated Next Diagnostic Steps to Consider Relative Cost: $$$$
with dilated cardiomyopathy in cats and some if Levels are Low
dog breeds (cocker spaniels, retrievers, and some Provide taurine supplementation, evaluate diet, Pearls
giant dog breeds such as Newfoundlands). consider potential causes of deficiency, monitor, Dogs can develop taurine-deficient dilated
Determination of plasma and/or whole blood address heart disease if needed. cardiomyopathy even on taurine replete diet;
levels of taurine may be useful in patients with poor bioavailability (e.g., binding by rice husks,
dilated cardiomyopathy that might benefit from Drug Effects intestinal malabsorption) and excess urinary
supplementation. Taurine-deficient cats (but Fasting may decrease plasma but not whole excretion of taurine precursors (e.g., cysteine)
not dogs) may develop degenerative retinal blood levels of taurine; therefore, whole blood proposed as mechanisms.
lesions. is preferred. Low taurine levels are not used as a screening
test for cardiomyopathy.
Reference Interval Lab Artifacts Breed differences may exist for taurine
• Plasma, cats and dogs: 60-120 nmol/mL Decreased levels. Example: Cocker spaniels with dilated
(critical level is <40) cardiomyopathy may not have blood taurine
• Whole blood, cat: 300-600 nmol/mL (critical Specimen Collection and Handling levels below the reference interval, yet still may
level is <200) • Whole blood: 1 mL heparinized whole blood benefit from taurine supplementation.
• Whole blood, dog: 200-350 nmol/mL (green top tube). Do not spin or separate;
(critical level is <150) refrigerate sample. AUTHOR & EDITOR: Lois Roth-Johnson, DVM, PhD,
DACVP
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