ABSTRACT
The causes of renal function impairment in patients with MM are summarized in Table 22.1. The commonest cause
of renal damage is cast nephropathy (myeloma kidney), which results from the production and excretion of free light chains (Bence Jones protein) and leads to tubular damage and progressive renal failure that may suddenly be worsened by precipitating factors. In contrast, the clinical pattern of deposition of light chains in the glomeruli is a nephrotic syndrome with or without renal failure. The structural differences in the light chains are responsible for the different potential toxicity for the glomerular basement membranes or the distal tubules; for this reason, the kidney usually shows only one pattern of involvement.11,12
The main cause of renal insufficiency in patients with MM is the so-called ‘myeloma kidney’ owing to light-chain tubular damage. More than 50% of patients with multiple myeloma have light-chain urine protein excretion.2
