Or for that matter, any significant bleed including intra-op bleeds ! About 200-250mg of precious Iron is lost with every 1/2 liter blood loss (at least external blood loss) while our bodies take a considerable time (months) to replenish lost Iron naturally from diet. Iron absorption via GI track is painfully slow – from just from a regular diet , adult men absorb maybe 1mg all day (1.5 mg in menstruating ladies) while with iron supplements maximum reported is up to 6 mg a day!
I remember a patient admitted with GI bleed from a peptic ulcer, with Hemoglobin being down from 13 on admission to 8.5 on discharge, prescribed Omeprazole on discharge and re-admitted from a clinic visit after 2 months with Hemoglobin down to 6.5. Naturally, recurrent GI bleed was suspected but there was no GI bleed this time – instead iron deficiency anemia had developed due to iron loss from the previous GI Bleed. Indeed the MCV was 94 during the first admission but down to 82 during second admission. It also did not help that patient didn’t qualify for blood transfusions during first admission based on GI bleed transfusion guidelines.
A randomized control trial published in 2014 showed iron supplementation (irrespective of IV v/s Oral) had a 2 gm/dL higher Hemoglobin after 4 weeks compared to placebo. This 2020 literature review by GI experts goes over guidelines for considering Iron replacement in GI bleeders including IV Iron. This 2016 paper goes over why clinicians underdiagnose iron deficiency in GI bleeders.
While I always check iron studies after any significant bleed (even if already received blood), I personally don’t think iron studies would always show iron deficiency in an acute bleed setting in a previously non-anemic patient. It takes time to drop Iron sats / ferritin levels – perhaps days. I haven’t found an accurate time-trajectory for this, but this 2021 paper about a study tracking Ferritin levels after repeat blood donations could help demonstrate that.
💡 Take Home points:
– After any significant blood loss that drops hemoglobin, highly consider Iron supplementation ( irrespective for what iron studies show for acute bleeds at least ) – especially if blood wasn’t transfused.
– Consider adding IV iron infusion if iron studies already show iron deficiency, if patient was anemic prior to bleed, if Hemoglobin drops close to transfusion cut-off or if patient has a history of poor oral intake, medication non-compliance or GI issues that affect absorption.
