Iron Deficiency in Inflammatory Bowel Disease: The Use of Zincprotoporphyrin and Red Blood Cell Distribution Width

Objectives: Iron deficiency (ID) in children with inflammatory bowel disease (IBD) is either an absolute (depleted iron stores) or a functional deficiency (caused by chronic inflammation). Differentiating between these 2 types of ID is important because they require a different therapeutic approach. Zinc protoporphyrin (ZPP) and red blood cell distribution width (RDW) are parameters of functional ID. Studies using these parameters to differentiate are nonexistent. We aimed to evaluate the prevalence of and risk factors for absolute and functional ID in paediatric IBD patients while using ZPP and RDW. Methods: We evaluated the iron status and medical charts of 59 paediatric IBD patients in a secondary hospital in the Netherlands. Absolute ID was defined as serum ferritin <15&hairsp;μg/L in the absence of infection and/or acute inflammation (C-reactive protein <10&hairsp;mg/L). Iron deficiency anaemia (IDA) was defined as absolute ID in combination with anaemia. Functional ID, in patients without absolute ID, was defined as ZPP >70&hairsp;μmol/mol haem and/or an RDW >14%. Anaemia of chronic disease (ACD) was defined as functional ID in combination with anaemia. Results: Absolute and functional ID were found in 19/59 (32.2%) and 32/40 (80%) patients, respectively. The prevalence of IDA and ACD was 27.1% (16/59) and 20% (8/40), respectively. Multivariate analyses showed that absolute ID and IDA were both associated with a more recent IBD-diagnosis (both P < 0.05). Conclusions: Absolute and functional ID are common in paediatric IBD patients, and this differentiation is important because of therapeutic consequences. Furthermore, absolute ID and IDA are associated with a more recent IBD-diagnosis.