These results suggest that impaired megalin-mediated absorption of the 25(OH)D-DBP complex plays an important role in the reduction of serum 1,25(OH)2D and 24,25(OH)2D in CKD, because of their restricted absorption of 25(OH)D into PTECs, although the resultant reduction of 1,25(OH)2D might decrease megalin expression in PTECs37. Here, LRP2 is linked to chronic kidney disease.