Association of the C-reactive protein–triglyceride glucose index with albuminuria and macroalbuminuria: A population-based cross-sectional analysis

The C-reactive protein–triglyceride glucose index (CTI) is a novel marker that integrates systemic inflammation and insulin resistance, both of which are associated with renal injury. However, population-based data on its associations with albuminuria and macroalbuminuria remain limited. This cross-sectional study analyzed data from 15,163 US adults in the National Health and Nutrition Examination Survey 1999 to 2010. CTI was calculated as follows: 0.412 × ln(C-reactive protein [mg/dL]) + ln([triglycerides (mg/dL) × fasting glucose (mg/dL)]/2). Albuminuria and macroalbuminuria were defined as urinary albumin-to-creatinine ratio ≥30 mg/g and ≥300 mg/g, respectively. Multivariable logistic regression, adjusted for confounders, assessed the associations. Smooth curve fitting and threshold effect analysis revealed nonlinear associations. Subgroup and interaction analyses examined consistency. Receiver operating characteristic curves and area under the curve compared CTI’s predictive performance with other triglyceride-glucose (TyG)-related indices. The prevalence of albuminuria and macroalbuminuria among participants was 12.46% and 1.92%, respectively. Higher CTI was associated with increased risk (albuminuria: odds ratio 1.22, 95% confidence interval: 1.14–1.31; macroalbuminuria: odds ratio 1.43, 95% confidence interval: 1.22–1.68). Nonlinear analysis showed a U-shaped curve with an inflection point at CTI ≈ 8.00. The positive associations remained robust across all subgroups (age, sex, body mass index, hypertension, diabetes, physical activity, estimated glomerular filtration rate). CTI outperformed other TyG indices in receiver operating characteristic/area under the curve for predicting both outcomes. This cross-sectional analysis demonstrates a U-shaped association of CTI with albuminuria and macroalbuminuria, offering superior risk identification compared with traditional TyG markers.