AMBP and chronic kidney disease: 83,84 The t1/2 of α1M in blood is believed to be roughly 1–3 minutes,85 and most free α1M is reabsorbed by proximal tubule cells and catabolized into the urine after it is nearly freely filtered past the glomerular membranes because of its small size.86 However, some α1M is excreted in the urine, which could be a useful clinical marker for renal tubular injury.86 Excessive excretion of α1M is considered a sensitive indicator of impaired renal tubular function87 and a marker of the severity of CKD progression.88