Tubular Dysfunction

Free light chains (Bence Jones protein) play a crucial role in causing renal damage in myeloma patients. The nephrotoxicity of certain light chains has previously been demonstrated. Incubation of light chain with renal cortical tissue slides inhibited organic ion trans-

Table 82.2

Reversible

Renal dysfunctions

Irreversible (mostly)

Volume depletion Hypercalcemia

Myeloma cast nephropathy Renal amyloidosis

Hyperuricemia Immunoglobulin deposition

Renal tubular acidosis diseases Hyperviscosity syndrome Myeloma cell infiltration Pyelonephritis port, gluconeogenesis, and ammonia formation,43 while microperfusion of nephrons with light chain isolated from myeloma patients with renal failure, but not those with normal renal function, led to obstruction of the distal tubules and cast formation.44 Furthermore, intraperitoneal injection of light chains from myeloma patients with a variety of renal lesions reproduced similar lesions in mice in 22 of 27 cases. Light chains from patients without renal disease were much less likely (4/13) to induce renal lesions.45 Thus, the properties of any particular light chain dictate the nature of renal damage in myeloma renal diseases.

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