What are causes of pre-analytical variation?
Answer:
stress-splenic contraction causes haemoconcentration, lymphocytosis in cats and horses, stress leukon; exertion-increases CK, LDH, ALT, AST, haemoconcentration; diurnal variation-hormone levels
anticoagulant: EDTA, Na citrate or F- can increase K or NA, decrease Ca inhibit enzymes
hemolysis: release of Hb freq causes positive or negative interference
lipemia: may produce turbidity interference w/ assays or spurious increase by displacing Whater
late separation of plasma or serum enhances glycolytic effects: decreased glucose, increased lactate, phosphaekk