Iron deficiency and elective cardiac surgery: Prevalence, diagnosis and bone marrow iron repletion following intravenous iron

Iron is essential for oxygen-transport and many other cell functions.

When done, blood tests suggest that up to 50% of patients scheduled for cardiac surgery, with or without anaemia, have iron deficiency (ID), which is associated with an increase in blood transfusions, longer intensive-care stays and worse outcomes. However, patients are not routinely investigated for ID prior to surgery.

Assumptions about the benefits and risks of iron replacement should be tested before widespread intervention.

In addition, uncertainties about how to define ID using blood markers should be addressed before launching a definitive therapeutic trial.

Bone-marrow biopsy is the gold-standard test for ID, and can be done painlessly during surgery.In patients scheduled for cardiac surgery, we will:Describe the prevalence of ID using various definitions based on blood markers alone.Investigate the accuracy of blood markers to identify ID assessed directly from bone-marrow obtained peri-operatively, thereby refining current definitions of ID based on blood markers.Conduct a randomised trial prior to surgery to demonstrate the ability of intravenous iron to replenish bone marrow iron stores.This research will inform the design of a large multicentre trial of iron replacement in patients with ID awaiting cardiac surgery.