Prevalence of iron overload vs iron deficiency in multiple myeloma: resembling or different from MDS--and stem cell transplant (SCT)--patients?

BACKGROUND: Most MM patients develop anemia with progression to symptomatic disease. Usually, this is normocytic/normochromic, with normal or low iron and elevated ferritin levels. Because ferritin levels alone do not correctly reflect iron stores, we performed a comprehensive analysis of iron parameters (iron, ferritin, transferrin, transferrin saturation [TRFS]) to more precisely assess patients' iron metabolism. PATIENTS AND METHODS: We analyzed: (1) the frequency of IO vs. ID in 136 consecutive MM patients; (2) the prognostic effect on progression-free (PFS) and overall survival (OS); and (3) specific risk groups according to patients' iron metabolism.
RESULTS: Most patients had normal iron metabolism or ID: median iron, ferritin, transferrin, and TRFS values were 75 μg/dL, 446 μg/L, 195 mg/dL, and 26%, respectively. Ferritin levels of < 400 μg/L, 400 to 1000 μg/L, and > 1000 μg/L were observed in 46%, 30%, and 24%, and TRFS levels < 20%, 20% to 45%, and > 45% in 32%, 46%, and 22% of patients, respectively. When patients with modified (ID or IO) vs. normal iron metabolism were compared, laboratory parameters (prohormone of brain natriuretic peptide, estimated glomerular filtration rate, c-reactive protein, reflecting cardiac, renal, or infectious impairment), and PFS and OS appeared impaired with modified metabolism, albeit age- and disease-specific differences were insignificant.
CONCLUSION: Normal iron metabolism and ID is more frequent in MM patients than IO. ID and IO correlate with organ impairment and impaired survival in MM. This knowledge should be incorporated into the design of future studies that will determine the benefit of iron supplementation with ID, and iron chelators with IO in MM.