Tubulointerstitial disease Types of tubulointerstitial renal disorders in multiple myeloma include Myeloma kidney (myeloma cast nephropathy) Acquired Fanconi syndrome (proximal tubular disease) Interstitial light chain deposition, causing acute tubular necrosis Light chains saturate the reabsorptive capacity of the proximal tubule, reach the distal nephron, and combine with filtered proteins and Tamm-Horsfall mucoprotein (secreted by cells of the thick ascending limb of Henle) to form obstructive casts.