Can Response to Iron therapy in ICU be predicted

Anemia in the Intensive Care Unit is a common problem. Transfusion triggers are getting lower across specialties as discussed last week. Iron infusion therapy is sometimes used to augment the marrow response to the stress of critical illness. But, the effect of iron therapy on reducing the transfusion requirement has not been reported. Litton et al attempted to evaluate the efficacy of Hepcidin in predicting the response to iron therapy and thereby reduce transfusion requirements. This was a nested cohort as a part of the IRONMAN study.

Hepcidin predicts response to IV iron therapy in patients admitted to the intensive care unit: a nested cohort study.

Litton et al. Journal of Intensive Care (2018) 6:60

This was a prospective observational study across four tertiary care Australian ICUs which participated in the IRONMAN study.
The response to Iron therapy among critically ill patients is variable. Hepcidin is an integral part of the iron metabolism and serum levels fall in iron deficiency states.
The primary aim of this study was to determine whether low serum hepcidin concentration could identify a subset of critically ill patients with anaemia in whom IV iron therapy was effective in reducing RBC transfusion requirement.
Septic patients and those with well established Iron deficiency were excluded.
The treatment arm received 500 mg IV ferric carboxy maltose. Hepcidin 25 levels were measured prior to administration of parenteral Iron
A total of 133 patients were included in this study
Majority of the patients were post operative patients predominantly from trauma and cardiothoracic ORs. APACHE II score was 12 and mean SOFA score was 6. Eighty eight patients fell in the lower two tertiles of hepcidin concentration. Half of them received parenteral iron and the other half received placebo. Patients who had lower hepcidin concentration responded to Iron and required lesser packed cell transfusions. Patients who had Hepcidin concentration in the highest tertile did not show any decreased requirement for blood transfusion despite iron therapy. Hepcidin levels did not correlate with standard determinants of iron deficiency like transferrin saturation index.
     The authors surmised that serum hepcidin concentration identified a subset of anaemic, critically ill patients in whom IV iron therapy was effective in reducing RBC transfusion requirement.

What I understood?
     Predicting response to iron therapy is always difficult and unpredictable. Using the Hepcidin level, if response to therapy can be predicted, lot of blood transfusions can be safely avoided

Where this study fails?
No septic patients included
No correlation with perfusion markers.