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1352 Hemoglobinuria and Hematuria Hemolysis

Specimen Collection and Handling Pearls used interchangeably with “erythrocytosis,”
EDTA anticoagulated blood (lavender top • The differences between HCT and PCV the correct term to indicate an increase in
VetBooks.ir tubes must be completely filled. Transport at at very high values (PCV/HCT > 65%), AUTHOR: Fidelia R. Fernandez, DVM, MS, DACVP
values are not clinically significant except
HCT.
tube); two capillary tubes for PCV; Vacutainer
where plasma trapping becomes substantial.
room temperature or refrigerate.
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
circulating cell lines, but this term is often
Relative Cost: $ • “Polycythemia” refers to an increase in all

Hemoglobinuria and Hematuria

Definition Causes of Abnormally High Levels Drug Effects
Hemoglobinuria is the presence of hemoglobin • Hemoglobinuria: severe intravascular hemo- Drugs causing intravascular hemolysis can also
in urine and is associated with red to brown lysis. Free hemoglobin also may appear in result in hemoglobinuria.
urine that persists in the specimen even after urine in cases of hematuria if erythrocytes
centrifugation. Hematuria is the presence of lyse in very dilute (specific gravity ≤ 1.008) Specimen Collection and Handling
erythrocytes in urine and is associated with red, or alkaline urine. Urine (5 mL) in a clean specimen container.
cloudy urine that clears with centrifugation. • Hematuria may be associated with urinary Indicate collection method.
Either one may cause a positive reaction on tract hemorrhage, trauma, infection, inflam-
the blood reagent square of a urine dipstick. mation, or bleeding neoplasia (p. 1229). Relative Cost: $ (reported as part of
standard urinalysis)
Physiology Next Diagnostic Steps to Consider
• Free hemoglobin in the plasma binds if Levels Are High Pearls
haptoglobin; the complex is cleared in the • Hemoglobinuria: identify cause of hemolysis • Avoid cystocentesis if gross hematuria
liver. When haptoglobin becomes saturated, by blood smear evaluation for hemic parasites, appreciated until coagulopathy and bladder
free hemoglobin splits into dimers that are Heinz bodies, eccentrocytes and spherocytes. neoplasia have been ruled out.
excreted by the kidneys. Hemoglobin in Evaluate CBC, serum biochemistry profile, • Cystocentesis and catheterization are
glomerular filtrate is absorbed by proximal RBC enzyme deficiency, and abdominal and frequently associated with iatrogenic,
tubules and metabolized to bilirubin, iron, thoracic imaging for triggers of hemolytic microscopic hematuria. These collection
and globin. Unabsorbed hemoglobin appears anemia. Evaluate history for spider bite, methods are not recommended for monitor-
in urine (hemoglobinuria). viper/coral snake envenomation, bee sting ing remission or progression of hematuria.
• Erythrocytes may appear in the urine from or exposure to toxins. • Free-catch urine from bitches in heat
upper urinary (renal, rarely ureteral), lower • Hematuria: rule out coagulopathy. Determine (proestrus) may also be contaminated with
urinary (bladder, urethra), urogenital (pros- when hematuria occurs during micturition blood.
tate, testes, prepuce, uterus, vagina, vulva), (beginning of urination suggests lower • A urine reagent strip that is positive for blood
or artifactual (traumatic sampling) sources. urinary/genital origin; end of urination, in the absence of red cells on urine sediment
bladder origin; throughout urination suggests warrants evaluation for hemoglobinuria or
Reference Interval renal disease, diffuse bladder disease, prostatic myoglobinuria (p. 1367).
• Hemoglobin is not found in normal urine. disease). Renal/bladder ultrasonographic
• Finding < 5 erythrocytes/HPF is considered evaluations often helpful. See pp. 428 and AUTHOR: Fidelia R. Fernandez, DVM, MS, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
normal in urine sediment. 1229.

Hemolysis

Definition of normal substances in serum, or leakage creatine kinase, lactate dehydrogenase,
Hemolysis is rupture of erythrocytes, releasing of analytes from erythrocytes. The degree of triglycerides, and total protein.
hemoglobin. It results in red discoloration of hemolysis may affect some analytes more than • Hemolysis causes an artifactual decrease in
serum or plasma. others (see individual test entries in this section RBC count, hematocrit, glucose, creatinine,
of the textbook). The analytes affected and total bilirubin, bile acids, alkaline phospha-
Physiology degree of interference depend on the method tase, gamma-glutamyltransferase, amylase,
Hemolysis is most commonly an in vitro artifact and type of analyzer. and lipase.
from traumatic venipuncture or improper
sample handling. It may also occur in vivo with Lab Artifacts Pearls
pathologic erythrocyte injury (especially intra- • Hemolysis causes an artifactual increase in Ways to prevent in vitro hemolysis include:
vascular injury). Hemolysis may interfere with hemoglobin, mean corpuscular hemoglobin • Avoid traumatic venipuncture.
laboratory assays by sample discoloration, alter- concentration, calcium, potassium, alanine • Avoid using a needle with an inappropriately
ing spectrophotometric assay results, dilution aminotransferase, aspartate aminotransferase, small diameter. Use a 21-gauge or larger

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