SUMMARY
Hermann’s tortoises (Testudo hermanni) are popular pets. Blood biochemistry is an essential tool for the early diagnosis of the diseases. The objective of the study was to investigate the biological variations in selected blood biochemical values in healthy tortoises through repeated samplings in the same animals. We also aimed to evaluate the values in time-related manner of sampling. Blood samples were taken five times (in two-month intervals) from the dorsal coccygeal vein. Twelve clinically healthy 2,5 year- old male tortoises were housed indoors. For each dataset, the mean, the standard deviation and the 95\% confidence interval of the mean were calculated. Mixed effect linear model was fitted with blood parameters as response variables, samples as fix factors and individuals as random factors. The mean levels and standard deviations are as follows: Ca, 2.3 ± 0.3 mmol/l; ionized Ca, 1.3 ± 0.4 mmol/l; P, 1.1 ± 0.3 mmol/l; uric acid, 121.1 ± 56.3 µmol/l; AST, 76.8 ± 42.8 IU/l; sodium, 127.7 ± 4.0 mmol/l; potassium, 4.5 ± 0.6 mmol/l. Except AST, sampling time had significant effect on the parameters. Despite the statistically significant difference between the collected samples, standard deviations were small in all samplings except for the uric acid. Accordingly, the clinical relevance of the sampling seems to be important especially for uric acid. In order to eliminate the possible effects of the time of sampling, repeated measurements are recommended if biochemical parameters are not in the reference intervals.