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1314 Bilirubinuria Blastomyces Testing

Bilirubinuria
VetBooks.ir Definition Causes of Abnormally High Levels

hyperbilirubinemia.
The presence of bilirubin, usually conjugated, • Cholestatic disease (impaired bile flow) or healthy dogs, and bilirubinuria can precede
in urine biliary rupture allows conjugated bilirubin
to leak into systemic circulation, with Lab Artifacts
Physiology subsequent renal excretion. False-negative reactions can occur with high
The mononuclear phagocyte system degrades • Excessive hemolysis (extravascular or intra- concentrations of ascorbic acid or nitrite
hemoglobin from senescent erythrocytes into vascular) leads to increased hemoglobin (urinary tract infection), delayed sampling (due
iron, amino acids, and unconjugated bilirubin. breakdown and bilirubin formation. to hydrolysis of bilirubin to the undetectable
Hydrophobic in nature, unconjugated bilirubin unconjugated form), and exposure to UV
must be albumin-bound for transport to the Next Diagnostic Steps to Consider light (which converts bilirubin to undetectable
liver for conjugation. Conjugated bilirubin if Levels Are High biliverdin).
is water-soluble, transported to bile for fat In dogs, assess degree of bilirubinuria and urine
emulsification, and degraded to urobilinogen concentration as limited bilirubinuria can be Specimen Collection and Handling
by the intestinal tract. Conjugated bilirubin normal in the species. Rule out a hemolytic Process or refrigerate within 30 minutes.
and urobilinogen can be absorbed into the anemia (e.g., decreased hematocrit, morphologic
portal circulation and become recycled for changes such as spherocytes, reticulocytosis). Relative Cost: $ (as part of urinalysis)
biliary excretion or remain in the plasma to Evaluate a biochemistry panel for cholestasis
be filtered by the glomerulus. Unconjugated (elevated alkaline phosphatase, gamma-glutamyl Pearls
bilirubin is not freely filtered by the glomerulus, transferase, total bilirubin, and/or cholesterol). Bilirubinuria is never normal in cats
as it is albumin-bound. See p. 528.
AUTHOR NAME: Shannon D. Dehghanpir, DVM, MS,
Reference Interval Important Interspecies Differences DACVP
• Trace to 1+ bilirubin can be observed in Dogs have a low renal threshold for bilirubin; EDITOR NAME: Lois Roth-Johnson, DVM, PhD, DACVP
concentrated urine of healthy dogs additionally, canine renal tubular epithelium
• Any degree of bilirubinuria is significant in has the ability to conjugate bilirubin. Thus,
cats low levels of bilirubin can be observed in

Blastomyces Testing Bonus Material
Available

Definition Causes of Abnormally High Levels negative, consider cytology/histopathology of
Blastomycosis is a systemic fungal infection A positive AGID test indicates exposure to lesions, repeat urine and serum EIA antigen
caused by the dimorphic fungus Blastomyces Blastomyces. A positive EIA antigen indicates test in 1-2 weeks, or IgG antibody EIA test.
dermatitidis. Blastomyces infection or infection with a cross-
reactive fungus (e.g., histoplasmosis). Drug Effects
Physiology Effective antifungal treatment will decrease
Inhalation of Blastomyces spores results in a Next Diagnostic Steps to Consider antigen levels in EIA test.
primary lung infection. Subsequent dissemina- if Levels Are High
tion occurs via blood and lymphatics to multiple Correlate results with clinical signs and Lab Artifacts
tissues, most notably skin, eye, bone, and lymph radiographic findings. Demonstration of the Interfering substances for the EIA test include
nodes. organism in cytologic or tissue biopsy samples Sputolysin, sodium hydroxide, EDTA, rheuma-
is preferred for definitive diagnosis (cytology toid factor, and heterophile antibodies.
Reference Interval should be prepared from any enlarged lymph
• Consult the laboratory conducting the test nodes or draining skin tracts). Culture is slow Specimen Collection and Handling
for information regarding reference range to grow, requires special handling, and is rarely Submit 1 mL of serum (red top tube) for AGID
for agar gel immunodiffusion (AGID). performed. and ≥0.25 mL for EIA antibody test. Submit
• Reference range for enzyme immunoas- ≥0.5 mL urine (preferred sample), ≥1.2 mL
say (EIA) antigen test is < 0.2 ng/mL; Causes of Abnormally Low Levels serum (red top tube), ≥0.5 mL bronchoalveolar
0.2-0.9 ng/mL is a low positive (many Negative test result indicates lack of expo- lavage fluid, cerebrospinal fluid, or sterile body
false-positives; positive predictive value sure, early infection, inadequate immune fluid for EIA test. Sample for EIA is stable for
[PPV] 36%); > 1 ng/mL is moderate-high response to exposure or false-negative EIA 2 weeks at room temperature or 2°C-8°C, and
positive (infection highly likely; PPV 91%). antigen (10% of cases, mostly localized indefinitely if frozen.
Sensitivity and specificity reported as 93.5% infections).
and 98%, respectively. (EIA available at Relative Cost: $$ (AGID); $$$ (EIA)
MiraVista Diagnostics, www.miravistalabs Next Diagnostic Steps to Consider
.com) if Levels Are Low Pearls
If high clinical suspicion of Blastomyces • EIA antigen test has higher sensitivity than
spp. exists but AGID and antigen tests are AGID for diagnosing canine blastomycosis.

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