Stability of Complete Blood Count Parameters in Rats and Rabbits: Impact of Blood Sampling Volume and Storage Time on Analytical Reliability

BACKGROUND: In laboratory practice, complete blood count (CBC) analysis is not always immediate, and underfilled or overfilled blood tubes may yield misleading results. OBJECTIVES: To assess CBC stability in rats and rabbits over 24 h and determine the effect of under- or over-filled tubes on alterations in the results, demonstrating which indices remain reliable under these conditions. METHODS: vacuum tubes from rats (tubes: 0.5, 1.0, 1.5, 2.0 mL) and rabbits (tubes: 2.0, 2.5 mL). All tubes were stored at 4°C and analyzed at 0, 4, 8, and 24 h using a CBC analyzer. RESULTS: Statistically significant changes (p < 0.05) were observed: In rats, white blood cell (WBC), neutrophil, lymphocyte, monocyte, red blood cell (RBC), hematocrit (HCT), and hemoglobin (Hb) counts were sensitive to blood sampling volume and decreased with smaller volumes. WBC, neutrophil, RBC, HCT, and platelet (PLT) counts showed no statistically significant change within 24 h. In rabbits, blood sampling volume and storage time independently influenced WBC, neutrophil, lymphocyte, and Hb counts. RBC, HCT, and PLT counts showed no statistically significant change within 8 h. CONCLUSIONS: WBC, neutrophil, lymphocyte, RBC, HCT, and Hb are volume-sensitive in rats and rabbits, whereas PLT counts are unaffected by volume. Therefore, blood samples with insufficient or excessive fill may still be used for PLT measurement, but results for the other indices are not recommended.