Objective: To evaluate the relationships between total calcium and phosphorus and ionised calcium and phosphorus values in clinically healthy tortoises.

Methods: Jugular blood samples were obtained from 25 tortoises, as part of a health screen of the population. These comprised Hermann’s tortoises, Testudo hermanni boettgeri, spur-thighed tortoises, Testudo graeca ibera, marginated tortoises, Testudo marginata, and horsfield tortoises, Testudo horsfieldi. Plasma from these samples were analysed for total calcium, ionised calcium and phosphorus levels. These samples were taken in the immediate posthibernation period, before the onset of reproductive activity.

Results: Females exhibited statistically significantly higher levels of phosphorus. Ionised calcium and total calcium levels were elevated in females compared with males, but this was not statistically significant. Females did have statistically significantly higher calculated solubility indexes and statistically significantly lower ratios compared with males.

Clinical Significance: This study has provided an insight into the ratios and solubility indexes in tortoises, and this information may lead to further understanding of the significance of these parameters in chelonians.