Serum ferritin levels in new hemodialysis (HD) patients increase over time, a trend independent of intravenous iron use, exposure to erythropoiesis-stimulating agents (ESAs), and other potential confounders, according to researchers.
A team led by Kamyar Kalantar-Zadeh, MD, MPH, PhD, of the University of California Irvine, analyzed data from a 5-year (January 2007–December 2011) cohort of 81,864 incident US HD patients. They examined changes in ferritin averaged over 3-month intervals as well as ferritin trends across strata of baseline ferritin level, dialysis initiation year, cumulative intravenous (IV) iron and ESA use in the first dialysis year, and baseline hemoglobin level.
Among patients with baseline ferritin levels lower than 200, 200 but less than 500, and 500 but less than 800 ng/mL, the mean change in those levels following dialysis initiation was 29.7, 32.9, and 19.4 ng/mL per quarter (designated as “patient-quarter”), respectively, Dr. Kalantar-Zadeh and his colleagues reported online ahead of print in Nephrology Dialysis Transplantation. Among patients with baseline ferritin levels of 800 ng/mL or higher, mean ferrtin levels initially decreased by 7.5 ng/mL per patient-quarter. Mean serum ferritin levels decreased from 1,133.8 ng/mL in the first patient-quarter to 847 ng/mL in the third patient-quarter. From the fourth patient-quarter onward, however, the levels rose over time, similar to the rest of the baseline ferritin strata, the investigators stated.
Among patients starting HD in 2007, mean ferritin levels rose sharply in the first year of dialysis (56.4 ng/mL/year) versus the second year (13.7 ng/mL/year), after adjusting for case-mix, malnutrition-inflammation-cachexia syndrome, and IV iron use, Dr. Kalantar-Zadeh and his colleagues reported. The ferritin slope again rose sharply (20.1 ng/mL/year) in the fifth year of HD. Changes in ferritin levels over time among patients who initiated HD in 2008 and 2009 followed a pattern similar to those who started HD in 2007, according to the researchers.
In addition, serum ferritin levels increased over time across strata of IV iron use, ESA dose, and baseline hemoglobin levels.
In analyses stratified by cumulative iron use, mean ferritin levels rose among patients receiving iron, but declined in patients not receiving iron.