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Fibrinogen Fluid Analysis 1343

thrombin time, antithrombin, and D-dimer Specimen Collection and Handling citrate tube will interfere with accuracy of
the plasma assay.
levels • Serum assay: special tubes filled with • Traditional FDP assays do not differentiate
VetBooks.ir Important Interspecies Differences soybean trypsin inhibitor or aprotinin (light between fibrinolysis and fibrinogenolysis;
thrombin, or reptilase (snake venom) with
Plasma FDP testing is currently only validated
D-dimer assays are specific for fibrinolysis.
blue top tubes with yellow label)
in the dog
• Plasma assays: citrated (light blue top tube).
of DIC
Tubes must be completely filled. Most refer- • Most often used to help support diagnosis
Drug Effects ence laboratories will supply collection tubes.
Fibrinolytic drugs (e.g., streptokinase) can AUTHOR: Deborah G. Davis, DVM, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
increase FDP concentrations. Relative Cost: $$
Lab Artifacts Pearls
False increases can occur when FDP gen- • Serum (plain red top tube) specimens cannot
eration occurs during collection (traumatic be used because clot formation consumes
venipuncture). FDPs, lowering measurement. A clot in the

Fibrinogen

Definition if inflammatory leukogram is present), serum Specimen Collection and Handling
Glycoprotein important in hemostasis; a posi- biochemistry profile; if hyperglobulinemia, Quantitative measurement requires citrated
tive acute-phase protein that increases due to serum protein electrophoresis is warranted plasma. Centrifuge and remove plasma within 1
inflammation or tissue injury; important in (polyclonal gammopathy suggests inflammatory hour of collection and transfer to plain red top
tissue repair process; p. 1375). tube. Label as plasma. Test as soon as possible.
Stable at 2°C-8°C for 24 hours; freeze if there
Physiology Causes of Abnormally Low Levels is a longer time interval before testing.
Made in the liver; production is upregulated Increased consumption in disseminated
with inflammation or tissue damage (due to intravascular coagulation (DIC) or increased Relative Cost: $$
cytokines interleukin [IL]-1, IL-6, and tumor fibrinogenolysis, decreased hepatic fibrinogen
necrosis factor [TNF]). It is a nonenzymatic synthesis, inherited/congenital disorders (docu- Pearls
coagulation factor (factor I), cleaved (activated) mented in Bichon frisé, Bernese mountain dog, Fibrinogen can be measured by heat pre-
by thrombin to form fibrin and promote stable Lhasa apso, Vizsla, and collie). cipitation (not recommended in dogs and
clot formation. cats; unreliable for low fibrinogen), coagulation
Next Diagnostic Steps to Consider methods (quantitative), and immunologic assays
Reference Interval if Levels are Low (to detect rare dysfibrinogenemic disorders).
Dogs: 150-300 mg/dL; cats: 150-300 mg/dL Full coagulation profile (activated partial throm- Laboratory Tests
boplastin time, prothrombin time, thrombin AUTHOR: Deborah G. Davis, DVM, DACVP
Causes of Abnormally High Levels time, platelet count, and fibrinogen degradation EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
Major causes: dehydration (hemoconcentra- products [FDPs]) to assess for DIC. Serum
tion) and increased hepatic production due biochemistry profile and serum bile acids to
to inflammation or tissue damage. Can also evaluate hepatic function
increase with hyperadrenocorticism, pregnancy,
and nephrotic syndrome Drug Effects
Heparin can decrease fibrinogen concentration.
Next Diagnostic Steps to Consider
if Levels are High Lab Artifacts
Look for source of inflammation/tissue injury: False decreases can occur with hemolysis,
review history and physical exam; CBC (determine lipemia, and high levels of FDPs.

Fluid Analysis

Definition Physiology between these membranes serves as a lubricant.
The evaluation of fluid that accumulates in a The pleural, pericardial, and peritoneal cavi- An effusion or accumulation of fluid into a body
body cavity secondary to altered hemodynam- ties lie between two thin mesothelium-lined cavity will form with increased submesothelial
ics, decreased oncotic pressure, inflammation, serous membranes that cover the viscera and capillary permeability or hydrostatic pressure,
neoplasia, hemorrhage, or lymphatic disease body wall. Normally, a scant amount of fluid decreased submesothelial capillary oncotic

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