Multiple Myeloma



This plasma cell dyscrasia, which often pre­sents with bone pain and/or paraproteinuria, is associated with renal dysfunction at some time in about half of all patients . The etiol­ogies of renal insufficiency in multiple myeloma include a specific renal lesion known as “mye­loma kidney,” hypercalcemia, and an increased susceptibility to nephrotoxins.

“Myeloma kidney” refers to a unique renal le­sion that is associated with Bence-Jones protein­uria, the excretion of kappa and lambda light chains of immunoglobulins. The histopathology is that of tubular occlusion by broad, waxy casts composed of the paraproteins. A prominent tu­bular reaction with giant cells and atrophy is ac­companied by widespread round cell infiltration in the interstitium. Amyloid deposits may be seen in glomeruli and tubules. Renal insufficiency is common with this lesion.

Hypercalcemia is seen in at least one third of myeloma patients and often causes a vasopressinresistant hyposthenuria with polyuria. Volume depletion from the polyuria may cause reversible renal insufficiency. Levels of serum calcium greater than 12 to 13 mg/dl are commonly ob­served.

A common phenomenon in multiple myeloma is the increased occurrence of acute renal failure after exposure to agents such as radiocontrast media or aminoglycoside antibiotics. Patients with multiple myeloma should be kept well-hy-drated, with intravenous saline if necessary, whenever exposed to a nephrotoxic agent.





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