Poster Presentation Australian and New Zealand Obesity Society Annual Scientific Conference 2023

Enhancing the safety of intravenous iron in obesity and bariatric surgery patients (#206)

Joy Gailer 1 , Jody Rothmore 1 , Kathryn Robinson 2 , Rosemary Allin 1 , Lauren Wierenga 1 , Tricia Warrick 1 , Tania Colarco 1 , Debra Rowett 1
  1. Drug and Therapeutics Information Service (DATIS), SALHN, Oaklands Park, South Australia, Australia
  2. Consultant Haematologist, The Queen Elizabeth Hospital, CALHN, Woodville, South Australia, Australia

Iron deficiency (ID) secondary to reduced oral intake, hypoacidity of the remaining stomach and decreased enteral absorption is common in patients following bariatric surgery with a reported prevalence of 20-55%.1,2 ID pre-bariatric surgery is associated with increased length of stay and risk of severe ID anaemia (IDA) post-surgery.3 Obesity is associated with higher rates of ID and IDA compared to those with normal body weight,4,5 with impaired absorption of oral iron secondary to raised hepcidin levels in the setting of adiposity-associated inflammation.6,7

The efficacy of oral iron supplementation is hindered in obesity and post-bariatric surgery and intravenous (IV) iron therapy may be needed to replete iron stores. IV iron products, such as ferric carboxymaltose (FCM) and ferric derisomaltose (FDI), have demonstrated efficacy and are generally well tolerated. Important safety considerations with IV iron include hypophosphataemia and hypersensitivity reactions (HSR).  Hypophosphataemia is more common with FCM than FDI, with one study finding 29% of post-bariatric surgery patients developed hypophosphataemia secondary to IV FCM.8 Hypophosphataemia can cause significant symptoms in a small proportion of patients, and osteomalacia has been rarely reported after repeated infusions.9

All IV iron products are associated with HSR, with most reactions due to non-allergic complement activation on nanoparticles of free labile iron.10 Mild to moderate HSR are uncommon (incidence 1:100─1000) and include localised cutaneous reactions, injection site reactions, nausea, vomiting, abdominal cramping, dyspnoea, mild hypo/hypertension or tachycardia. Severe HSR are rare and include anaphylaxis and acute allergic coronary arteriospasm with infarction.10

Risk factor assessment is paramount to identify patients at increased risk of HSR and hypophosphataemia, and should be included in IV iron administration protocols to enable rapid identification and appropriate management.

This case-based presentation will discuss the identification of at-risk patients and the management of these adverse effects.