AOPEP and chronic kidney disease: A study comparing 55 patients with CKD (creatinine clearance <70 ml/min) and matched controls found that urinary apo(a) was lower among patients with CKD (44), suggesting that the kidney may be involved in clearing intact apo(a) from the circulation, in addition to clearing apo(a) fragments produced by proteases in various tissues and pre-renal degradation (45).