Iron Overload Increases Post-Transplant Infection Risk

BERLIN—Kidney transplant recipients who have iron overload are at increased risk for bacterial infection compared with those who have normal iron levels, according to preliminary results of a Spanish study.

The prospective study also revealed that ferritin levels above 500 ng/mL are associated with a higher risk of death within three years compared to lower ferritin levels.

“We are planning to assess the total body iron stores in kidney-transplant recipients using more accurate parameters such as serum hepcidin levels to confirm the preliminary findings that emerged from this study,” said lead investigator Mario Fernández-Ruiz, MD, of the University Hospital “12 de Octubre” in Madrid, after presenting the results at the 24th International Congress of The Transplantation Society. If the findings are corroborated, “monitoring of serum iron markers may have a role in predicting adverse outcomes after kidney transplantation,” Dr. Fernández-Ruiz said.

The likely link is iron's important role in the survival and virulence of many potentially pathogenic microorganisms, he noted.

Dr. Fernández-Ruiz and his colleagues focused their analysis on 228 patients who received kidney transplants from November 2008 to February 2011. Their average age was 54.9 years, 60.5% were men and their pre-transplant conditions included glomerulonephritis, diabetic nephropathy, renal polycystosis and hypertensive nephrosclerosis. Just 10 (4.4%) received a living-donor transplant. The mean cold ischemia time was 16.8 hours.

Infection occurred in 153 patients (67.1%) after transplantation. Most of the infections (117) were bacterial, but there were 73 cytomegalovirus infections and 17 fungal infections.

Ninety-two subjects (40.4%) had an iron overload, defined as serum ferritin levels above 500 ng/mL at baseline. They had a significantly greater incidence of bacterial infection than patients without iron overload. In adjusted analyses, iron overload was associated with a 41% increased risk of any infection and a 57% increased risk of bacterial infection.

Furthermore, although total iron-binding capacity did not differ significantly between the patients who did and did not have any type of infection, it was significantly lower in those with a bacterial infection compared with those who did not.

The only other factor found to be significantly associated with bacterial infection was acute graft rejection, the researchers reported. Reoperation during the first post-transplant month and poorer graft function at 30 days post-transplant were significantly associated with a higher risk of any type of infection.

Post-transplant infection-free survival was significantly shorter in recipients with iron overload compared with those who did not have iron overload (134 vs. 188 days). Patients with iron overload also had a significantly greater all-cause mortality rate (12.0% vs. 4.4%).

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