Common interferences (hemolysis from rupturing of RBCs, 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.
|Hemolysis (rupturing of RBCs)||↓ 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 in vitro 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 from leukocyte swelling (false left shift), apoptosis and false toxic change, ↓ platelet count, ↑ MPV, echinocyte formation, in vitro 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 (does not eliminate changes in MCV, HCT, MCHC, WBC, platelet count, MPV; just allows more accurate blood smear examination, e.g. differential leukocyte count)|
|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 (zonisamide can also do this)||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)|