Patients with chronic kidney disease (CKD) and abnormal iron balance are more likely to die early, according to new study findings.

Monique E. Cho, MD, of the University of Utah in Salt Lake City, and collaborators stratified 32,489 mostly male veterans with nondialysis CKD (mean age 72 years), matched by propensity scoring, into 4 iron groups defined by a combination of serum transferrin saturation (TSAT) and ferritin levels. The reference group had TSAT 16%-28% and ferritin 55-205 ng/mL. Other groups included those with low iron (0.4%-16% and 0.4-55 ng/mL), high iron (28%-99.6% and 205-4941 ng/mL), and function iron deficiency (0.8%-16% and 109-2783 ng/mL), respectively. A third of the entire cohort had absolute or functional iron deficiency.

Investigators found increased risk for all-cause mortality by 21%, 10%, and 9% for the functional iron deficiency, low, and high iron groups, compared with the referent, over 4 years of follow-up. Those with and without diabetes had similar death risks within each iron group.

“Our data support previously published studies that iron deficiency increases mortality risk independent of anemia in non-CKD populations, given that hemoglobin level was well matched among the iron groups in our study,” Dr Cho and her colleagues wrote in Kidney International.

The results have important implications for iron management in CKD, even prior to development of anemia. “Given our result that iron deficiency is associated with mortality independently of hemoglobin levels in CKD, and given the similar finding in HF [heart failure], early screening of iron indices may improve CV [cardiovascular] risk assessment and optimization of treatable CV risk factors in pre-dialysis CKD.”

It remains unclear whether iron, rather than inflammation, leads to increased mortality.

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Reference

Cho ME, Hansen JL, Peters CB, et al. An increased mortality risk is associated with abnormal iron status in diabetic and non-diabetic veterans with pre-dialysis chronic kidney disease. Kidney Int. doi:10.1016/j.kint.2019.04.029