B2M and stage 5 chronic kidney disease: [1,2] It has long been appreciated that glomerular filtration is the major pathway for the elimination of β2M. [3–7] Residual renal function (RRF), inflammation and malnutrition appear to affect β2M concentration in patients with chronic kidney disease (CKD) [8–11] and end-stage renal disease (ESRD) [12–17]