Plasma and urinary F-isoprostane markers of oxidative stress are increased in cats with early (stage 1) chronic kidney disease.

Abstract

OBJECTIVES: Oxidative stress contributes to chronic kidney disease (CKD) progression in humans and rodent models; F-isoprostanes (F-IsoPs) are established biomarkers of oxidative stress. Our primary aim was to evaluate plasma F-IsoPs in cats with International Renal Interest Society stage 1 and 2 CKD, compared with healthy cats, and to determine whether plasma and urinary F-IsoPs are equivalent biomarkers. The secondary aim was to assess whether consumption of a renal diet enriched in omega-3 fatty acids led to improvements in plasma and urinary F-IsoPs. METHODS: Plasma and urinary F-IsoPs were measured in 24 cats with stage 1 or 2 CKD, and 12 unaffected controls aged ⩾6 years. Twelve CKD cats were re-evaluated after feeding a commercial renal diet for at least 4 weeks. RESULTS: Median plasma F-IsoPs were significantly higher in stage 1 CKD (96.2 pg/ml), early stage 2 CKD (83.2 pg/ml) and late stage 2 CKD (80.8 pg/ml) compared with healthy cats (22.8 pg/ml; = 0.03-0.002). Median urinary F-IsoPs were significantly higher in cats with stage 1 CKD (231.2 pg/mg) compared with healthy cats (152.5 pg/mg) or cats with late stage 2 CKD (124.8 pg/mg; = 0.01). Plasma F-IsoPs remained increased, while urinary F-IsoPs fell with transition from stage 1 to stage 2 CKD. Feeding a commercial renal diet led to significant decreases in plasma F-IsoPs in the small group of cats with stage 1 CKD (25-75% decrease) compared with cats with stage 2 CKD (20% decrease to 53% increase; = 0.01). CONCLUSIONS AND RELEVANCE: Oxidative stress is prominent in cats with stage 1 CKD. Plasma and urinary F-IsoPs are not interchangeable biomarkers in cats with stage 2 CKD. Placebo-controlled studies are indicated to evaluate dietary or pharmacologic doses of omega-3 fatty acids on redox stress and progression of renal dysfunction in cats with stage 1 CKD.