Hemojuvelin and iron metabolism in kidney and heart allograft recipients

Introduction: Hemojuvelin plays an essential role in the regulation of hepcidin expression, specifically in the iron-sensing pathway. Dietary iron sensing and inflammatory pathways converge in the regulation of the key regulator hepcidin. Hepcidin is a small defensin-like peptide whose production by hepatocytes is modulated in response to anemia, hypoxia, or inflammation. We studied correlations of hemojuvelin with markers of iron status and of inflammation among 61 prevalent kidney allograft recipients and 136 prevalent heart transplant recipients. Methods: Complete blood count, urea, serum lipids, fasting glucose, and creatinine were measured using standard laboratory methods in the central laboratory of the hospital. Hepcidin, soluble transferin receptor (sTFR), interleukin-6 (IL-6) and hemojuvelin were assayed by enzyme immunosorbent assay using commercially available kits. Results: Among heart transplant recipients hemojuvelin correlated strongly with kidney function, transferrin saturation and white blood cell count; moderately with red blood cell count, hepcidin, IL-6, high-sensitivity C-reactive protein (hsCRP) and weakly with sTfR. Multiple regression analysis revealed the predictors of hemojuvelin to be kidney function and TSAT, explaining 79% of the variations among hemojuvelin values in heart transplant recipients. Among kidney transplant recipients hemojuvelin correlated with kidney function, TSAT, hepcidin and hsCRP, and tended to correlate with IL-6. Predictors of hemojuvelin on multiple regression analysis were TSAT and creatinine. Conclusions: Elevated hemojuvelin as well as hepcidin levels in kidney or heart transplant recipients may be due to the impaired kidney function and disturbed iron status frequently encountered among this population.