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Total Protein (Serum) Toxoplasma Serologic Testing 1387

Specimen Collection and Handling but at the low end of the reference • High T 4 is diagnostic for hyperthyroidism
interval.
Serum (red top tube), 1 mL. To avoid interfer- • Approximately 10% of cats with clinical in cats; fT 4 is more sensitive but less specific
VetBooks.ir centrifugation. Remove serum and transfer to hyperthyroidism have T 4 values within the • Unpredictable diurnal fluctuations in dogs
for the diagnosis, and should be interpreted
ence by fibrin, allow full clot formation before
along with TT4.
upper end of the reference interval due to T 4
plastic tube. Store refrigerated up to 7 days.
can slightly decrease T 4 values.
Frozen samples are stable for up to 1 month.
fluctuations. Recheck T 4 if hyperthyroidsim
suspected. • Ensure use of a standard or modified
Relative Cost: Total T 4: $; fT 4: $$ • Total T 4 within the reference interval sup- equilibrium dialysis fT 4 method.
ports euthyroidism in dogs, but a low T 4 is • Given assay variability, use one laboratory
Pearls not specific for hypothyroidism, as drugs for ongoing patient testing.
• T 4 and fT 4 can be markedly lower in sight- and nonthyroidal illness also decrease it.
hounds and older dogs; puppies up to 6 months • Free T 4 is not as likely as T 4 to be affected AUTHOR: Shelley Burton, DVM, MSc, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
and small breeds tend to have higher levels. by nonthyroidal illness or drugs, so a very
• Approximately 5% of dogs with clinical low level supports hypothyroidism.
hypothyroidism have T 4 values within
Total Protein (Serum)

Definition disease, chronic hepatic disease, nephrotic clinically, evaluate for gastrointestinal, hepatic,
Serum proteins consist of albumin, antibodies, syndrome, and neoplasia (myeloma, lymphoma, renal (glomerular) disease.
complement, enzymes, coagulation factors, lymphocytic leukemia, and rarely solitary
and transport proteins. Albumin and globulin plasma cell tumors). Increased albumin occurs Drug Effects
make up the majority of serum total proteins. with dehydration and is “relative.” • Increased: testosterone, estrogens, growth
Fibrinogen, factor V, and factor VIII are proteins hormone
present in plasma but not in serum, because Next Diagnostic Steps to Consider • Decreased: thyroxine, cortisol
they are utilized in clot formation. if Levels are High
Characterize hyperproteinemia by measuring Lab Artifacts
Synonym serum albumin and globulin levels; assess Increase (globulin fraction): lipemia, hemolysis,
Total solids, TP, TS hydration status; perform serum protein and hyperbilirubinemia
electrophoresis if hyperglobulinemia is absolute
Physiology (normal albumin level) and repeatable. Specimen Collection and Handling
The proteins in serum are important for Serum (red top tube) preferred. Heparinized
maintaining colloid osmotic pressure (primarily Causes of Abnormally Low Levels plasma (green top tube) or EDTA plasma
albumin), buffering to maintain blood pH, Low albumin without a decrease in globulins (lavender top tube). Stable for 1 month at
hemostasis, transport of molecules (hormones, occurs with protein-losing nephropathy and 2°C-8°C Laboratory Tests
drugs, calcium, bilirubin, hemoglobin, other chronic hepatopathies. Both hypoalbuminemia
proteins, lipids, and metal ions), acute-phase and hypoglobulinemia occur with protein-losing Relative Cost: Single test: $; included in
response to inflammation, and immune enteropathy, whole blood loss (gastrointestinal, many chemistry panels: $-$$
response. Most are synthesized in the liver or lacerations/trauma, other hemorrhage), exudative
immune system. skin disease, massive burns, and effusive disease. Pearl
Hypoglobulinemia with normal albumin occurs Reference intervals based on serum values.
Reference Interval with decreased immunoglobulin concentration If measured in plasma (heparin or EDTA)
Dogs: 5.1-7.8 g/dL. Cats: 5.9-8.5 g/dL. Unit due to failure of passive transfer or inherited samples, values may be slightly higher.
conversion: g/dL × 10 = mg/mL. or acquired immune deficiency.
AUTHOR: Ruanna E. Gossett, DVM, PhD, DACVP
Causes of Abnormally High Levels Next Diagnostic Steps to Consider EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
Increased globulin: acute and chronic inflam- if Levels are Low
mation or infection (rickettsial, bacterial, viral, Characterize hypoproteinemia by measuring
fungal, protozoal, parasitic), immune-mediated serum albumin and globulin levels. As indicated

Toxoplasma Serologic Testing

Definition Physiology tissue-encysted bradyzoites. Enteroepithelial
Toxoplasmosis is a protozoal disease caused by Transmission to cats and dogs occurs via phase of primary infection in the definitive
Toxoplasma gondii, an intracellular parasite that ingestion of tissue cysts within intermediate host (cat) results in fecal shedding of oocytes.
infects many tissues of birds and mammals, hosts. Most infections are latent with no Immunosuppression in the dog or cat may
including humans (p. 984). clinical signs, but infection persists for life as lead to cyst rupture, multiplication of

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