Although increased fractional excretion of phosphate, hypophosphatemia and normoglyacemic glycosuria are established markers of proximal tubular dysfunction and are easy to screen for, they are less sensitive than tubular protein excretions (NGAL, B2M and RBP) and have been suggested to be the most appropriate alternatives when these are not available [6, 34, 35]. This evidence concerns the gene B2M and hypophosphatemia.