Background: The cynomolgus monkey (Macaca fascicularis) has been increasingly used in biomedical research, making knowledge of its blood-based parameters essential to support the selection of healthy subjects and its use in preclinical research. As age and sex affect these blood-based parameters, it is important to establish baseline indices for these parameters on an age and sex basis and determine the effects of age and sex on these indices.
Methods: A total of 917 cynomolgus monkeys (374 males and 543 females) were selected and segregated by age (five groups) and sex. A total of 30 hematological and 22 biochemical parameters were measured, and the effects of age and sex were analyzed.
Results: Baseline indices for hematological and biochemical parameters were separately established by age and sex. Significant effects by age, sex, and age-sex interaction were observed in a number of blood parameters. In the 49-60 months and 61-72 months age groups, red blood cell count, hemoglobulin, and hematocrit showed significantly lower values (P<0.01) in females than males. Serum alkaline phosphatase varied with age in both sexes (P<0.01) and was significantly higher in females than males (P<0.05) in the groups aged 13-24 months and 25-36 months; however, in the three groups aged over 25-36 months, serum alkaline phosphatase was significantly lower in females than males (P<0.01). Creatinine concentration increased with age (P<0.01) in all age groups; specifically in the groups aged 49-60 months and 61-72 months, creatinine was significantly higher (P<0.01) in males than females. Total protein and globulin both increased with age (P<0.01).
Conclusion: The baseline values of hematological and biochemical parameters reported herein establish reference indices of blood-based parameters in the cynomolgus monkey by age and sex, thereby aiding researchers in selecting healthy subjects and evaluating preclinical studies using this species.