Common artifacts

 
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Common interferences (hemolysis, icterus, lipemia) and blood sample collection, handling and storage problems can affect the results of hematologic and clinical chemistry testing. A brief summary of common changes that we see is given below.

Common variables that may affect results of hematology and clinical chemistry testing*
Condition Hematology Chemistry Comments
Hemolysis ↓ HCT, ↓ PCV, ↓ RBC count, ↑ MCH, ↑ MCHC, ↑ platelet count, inaccurate total protein by refractometer (line difficult to read), ↑ ghost cells on blood smear Many effects, depending on degree and method (see individual chemistry test). Some changes are: ↑ K (horses, some breeds of cattle, sheep, some breeds of dogs, pigs, camelids), ↑ AST, ↑ iron, ↑ phosphate, ↑ LDH, ↑ magnesium, ↑ CK, ↑ zonisamide, ↓ amylase, ↓ GGT, ↓ ALP Gentle blood handling, minimize temperature extremes, clean venipuncture
Lipemia ↑ Hgb, ↑ MCH, ↑ MCHC, possible ↑ platelet count, ↑ total protein by refractometer, promotes hemolysis, distorts RBC morphology Variable effect depending on degree and method (see individual chemistry tests). Some changes are: ↓ Na, ↓ Cl, ↓ bicarbonate, ↓ LDH, ↑ magnesium, ↑ TIBC Collect fasting sample
Icterus None Variable, depending on degree and method (see individual chemistry test) Some changes are: ↓ creatinine, ↓ cholesterol, ↓ GGT
Storage ↑ MCV, ↑ HCT, ↓ MCHC, ↓ WBC, inaccurate differential cell count, ↓ platelet count, ↑ MPV, echinocyte formation, hemolysis Variable, depending on test and if separated from cells. Some enzymes are unstable with storage, e.g. SDH; if not separated from cells: ↑ K (see species above for hemolysis due to leakage from cells), ↓ glucose Store at 4°C and submit ASAP to laboratory, separate serum/plasma from cells, make fresh blood smears for hemograms
Excess EDTA ↓ MCV, ↑ MCHC, ↓ HCT, echinocyte formation Contamination: ↓ calcium, ↓ iron, ↑ K, ↓ enzyme activity (e.g. ALP) Fill blood tube to correct volume, don’t contaminate chemistry samples with EDTA (collect red or green top first)
Bromide treatment None ↑ chloride Inform the laboratory that animal is on bromide therapy (we can use a method that reduces this false increase)
Post-mortem samples Lysis of cells, bacterial contamination Increases are seen in many test results, particularly those found in high concentrations within cells. Examples include: ↑ K, ↑ calcium, ↑ AST, ↑ LDH, ↑ magnesium, ↑ phosphate, ↑ iron, ↑ CK, ↓ bicarbonate. For hematologic testing, the changes under hemolysis will apply, although leukocytes and platelets will also lyse after death. Don’t collect post-mortem samples (ocular fluid is an exception)

* See also interferences and interference indices.

 

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