CST3 and chronic kidney disease: 1. ImP is a common metabolite in patients with prediabetes/T2D, CHF, and CKD.2. ImP levels increase 1.1–1.6 times with each additional CHF comorbidity (e.g., NGT vs. NGT + CHF: FC = 1.1, P = 0.047; T2D + CHF vs. NGT + CHF: FC = 1.6, P = 0.055; T2D + CHF + CKD vs. T2D + CHF: FC = 1.5, P = 0.011).3. ImP strongly associates with CKD biomarkers, including creatinine, Cystatin C, and eGFR.