CST3 and chronic kidney disease: Shrunken pore syndrome (SPS) is defined as a difference in estimated GFR from cystatin C versus creatinine (eGFRCystatin C <60% eGFRCreatinine in the absence of non‐renal influence on the levels of cystatin C or creatinine [Grubb, 2020]), and has been identified as a strong independent risk factor for mortality in patients undergoing elective coronary artery bypass grafting (Dardashti et al., 2016) and CKD.