Critical differences of clinical chemical components in blood from laboratory rabbits

The purpose of the present study was to calculate the critical difference between two analytical results for 11 clinical chemical components in the adult rabbit. The critical difference can be used to judge whether the difference between two  consecutive analytical results from the same animal is due to natural variation or not. From 25 adult rabbits, blood samples were collected once daily after a 12 hour fasting period for 5 consecutive days, and the total variance of the analytical results of each clinical chemical component was divided into the component of variance between rabbits (S2inter), the component of variance for days within rabbits (S Intra), and the component of variance for measurements (S2Anal) using nested analysis of variance. The critical difference was then calculated from 521mm and SZAnal as 0.48 pkat/l for alanine aminotransferase (ALAT), 0.20 pkat/l for aspartate aminotransferase (ASAT), 2.32 ukat/l for alkaline phosphatase (AP), 3.57 ttkat/l for amylase, 5.69 mmol/l for urea, 26 pmol/l for creatinine, 6.6 g/l for albumin, 14.0 g/l for serum proteinTOml, 2.10 mmol/l for glucose, and 0.59 mmol/l for cholesterolTotal, and 4.60 mmol/l for lactate. These critical differences may be used as guidelines to evaluate the difference between two consecutive analytical results of the above clinical chemical components. However, the analytical results should not be assessed by the critical differences alone, but should also be compared to the corresponding population based reference intervals