Key result
Induced CKD in cats is linked to ~3-fold higher urinary angiotensinogen-to-protein ratios versus healthy controls.
Why the study?
To compare urinary angiotensinogen, a proposed biomarker for intrarenal RAS activity, between cats with surgically induced CKD and healthy cats, and explore its correlation with clinical and circulating RAAS markers.
Does surgically induced CKD increase urinary angiotensinogen levels in cats compared to healthy cats?
Observational (n=28)
Does surgically induced CKD increase urinary angiotensinogen levels in cats compared to healthy cats?
Absolute Event Rate: 9.8% vs 3.38%
Intrarenal RAS, assessed by urinary angiotensinogen, is activated in cats with induced CKD, highlighting the need for concurrent evaluation of circulating and intrarenal RAS markers.
Supports intrarenal RAS activation in feline CKD models; hypothesis-generating for concurrent RAS marker evaluation in future studies.
Objective: To compare urinary angiotensinogen, a proposed biomarker for intrarenal renin-angiotensinogen system (RAS) activity, between cats with surgically induced chronic kidney disease (CKD) and healthy cats and explore its correlation with select clinical and circulating renin-angiotensin-aldosterone system (RAAS) markers. Methods: Urine was banked from September 2022 through April 2023 during a study comparing circulating RAAS markers between cats with induced CKD and sex- and life stage-matched healthy cats. Urinary angiotensinogen concentration was measured from October 2025 through July 2026 using a validated in-house ELISA. Urinary concentration of angiotensinogen was indexed to that of creatinine or protein to account for urine concentration or indiscriminate urinary protein loss, respectively. Results: 28 cats (n = 14/group) were included. The median (IQR) indexed urinary angiotensinogen was higher in cats with CKD than in healthy cats (urinary angiotensinogen-to-protein ratio, 9.80 [5.47, 17.22] vs 3.38 [1.09, 5.52]; urinary angiotensinogen-to-creatinine ratio, 0.99 [0.40, 2.34] vs 0.31 [0.21, 0.60]). In cats with CKD, indexed urinary angiotensinogen correlated positively with serum creatinine concentration (urinary angiotensinogen-to-protein ratio, ρ = 0.573; urine angiotensinogen-to-creatinine ratio, ρ = 0.642). In healthy cats, urinary angiotensinogen-to-creatinine ratio correlated negatively with several circulating RAAS markers, including serum angiotensin II (ρ = -0.547) and angiotensin 1-7 (ρ = -0.631) equilibrium concentrations. Conclusions: The intrarenal RAS, assessed by urinary angiotensinogen, is activated in cats with induced CKD, and its activity is inversely related to that of the circulating RAAS in healthy cats but not those with CKD. Clinical Relevance: Concurrent evaluation of circulating RAAS and intrarenal RAS markers is required for complete assessment of this system.
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Huang et al. (2026) conducted an observational in Chronic kidney disease (n=28). Surgically induced chronic kidney disease vs. Healthy cats was evaluated on Urinary angiotensinogen-to-protein ratio. Surgically induced chronic kidney disease in cats was associated with higher median urinary angiotensinogen-to-protein ratios (9.80 vs 3.38) compared to healthy cats.
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