Acquired iron overload associated with antitransferrin monoclonal immunoglobulin: a case report.

We describe a patient with an unusual combination of hypersideremia (700 microg/dL), hypertransferrinemia (570 mg/dL), hyperferritinemia (800 microg/L), and monoclonal gammopathy of undetermined significance (MGUS), in which the monoclonal immunoglobulin showed specific transferrin-binding activity. Liver histology revealed hepatic iron overload, prominent in periportal hepatocytes, suggesting intestinal iron hyperabsorption. We demonstrate that low urinary hepcidin, likely due to impaired iron delivery to erythroid cells via the transferrin cycle pathway over time, may be the mechanism for iron loading. We suggest that MGUS associated with monoclonal antibodies with antitransferrin activity should be added to the list of acquired causes of hemochromatosis.