Serum chemistry values are often derived by spectrophotometrically measuring change in the amount of light transmitted through serum after a chemical reaction changes the color density of the sample by an amount relative to the concentration of the target substance (glucose, creatinine, or ALT for example). If the serum is hemolysed it changes the baseline color and there may be fragments of RBCs in the serum as well, interfering with the measurement of light in unpredictable ways. If the serum is lipemic, globules of fat may interfere with the measurement of light in unpredictable ways. With hemolysis, typically our lab sees marked elevations in total protein, albumen and phosphorus with variable increases in ALT, AST. T Bili, glucose, calcium and occasionally decreased creatinine and ALP. Lipemic specimens can have variably increased creatinine, ALT, AST. ALP. T Bili, glucose, calcium, phosphorus, and total protein.
CBC results can be affected by hemolysis due to decreased RBCs, and both hemolysis and lipemia can affect turbidometric values such as hemoglobin and the indices calculated from hemoglobin.
It is suggested that serum be centrifuged and separated from the blood to decrease in-vitro hemolysis and document lipemia. If the sample is lipemic, it might be helpful to wait a 4-8 hours and redraw the sample. Remind owners that feeding before a blood draw can cause inaccurate results.