Day to Day Variability and Effects of Collection Conditions on Urinary Renin‐Angiotensin‐Aldosterone System Biomarkers in Vervet Monkeys ( Chlorocebus aethiops sabaeus )

BACKGROUND: Dysregulation of the renin-angiotensin-aldosterone system (RAAS) is associated with cardiovascular and renal disease. Our objectives were to determine the daily variability in urinary RAAS biomarkers and differences between non-sedated free catch (FC) and sedated cystocentesis samples in vervet monkeys. METHODS: We performed repeated urine collections (six non-sedated FC, three sedated cystocentesis) from six adult vervets (Chlorocebus aethiops sabaeus). We quantified RAAS components, normalized to urine creatinine. We assessed variability using coefficients of variation (CV) and compared sedation effects using linear mixed-effects models with false discovery rate correction. RESULTS: Analytes showed high to very high variability (CV 28.17%-103.03%). Angiotensin converting enzyme demonstrated the lowest variability (cystocentesis, CV 28.17% ± 18.28%). Creatinine, Angiotensin-(1-7), Angiotensin II, and aldosterone concentrations differed between non-sedated FC and sedated cystocentesis samples. CONCLUSIONS: Substantial within-animal variability suggests that single-timepoint measurements insufficiently characterize urinary RAAS in vervets. Differences between collection conditions support standardization of collection methods and repeated sampling.