Urinary excretion of retinol in patients with multiple myeloma: a preliminary study

Urinary excretion of vitamin A was studied in patients with multiple myeloma (MM). Eight of the 12 patients studied excreted retinol in urine; only one of them had elevated serum creatinine (115-150 micromol/L). There was a highly significant correlation between urinary retinol and serum creatinine (P < 0.0004). Urinary retinol correlated also with urine protein (P < 0.0001) and albumin (P = 0.001), but not with urinary immunoglobulin light chains. Urinary retinol excretion may be an early manifestation of renal dysfunction in MM patients. The effect of urinary retinol excretion on vitamin A homeostasis in MM deserves further study.