From the Guidelines
After an iron infusion, patients may experience decreased appetite and weight gain despite a caloric deficit due to temporary gastrointestinal side effects, metabolic changes, and fluid retention, which are common side effects of iron infusions, as reported in a study published in 2018 1. The potential causes of these symptoms can be multifactorial. Iron infusions can cause gastrointestinal side effects like nausea, vomiting, and abdominal pain, which might affect appetite, as seen in various case series in adults, where 2-5% of patients experience significant side effects 1. Additionally, as the body's iron levels normalize, metabolic changes can occur, affecting how the body processes and stores energy.
- The weight gain might be due to fluid retention, which is a common side effect of iron infusions, rather than actual fat gain, and this fluid retention typically resolves within a few days to weeks after treatment.
- It is essential to note that iron sucrose, one of the most studied iron preparations in children, has been shown to have a low incidence of severe adverse events, and it is recommended for intermittent infusions 1.
- A more recent study published in 2022 1 suggests that iron supplementation should be tailored to individual needs, and IV iron administration is used to replace iron losses rapidly in patients not reaching target therapeutic goals with oral supplementation.
- The study also highlights the importance of risk minimization when using IV iron, as reactions during iron infusions are very infrequent but may be life-threatening 1. If these symptoms persist beyond 2-3 weeks post-infusion, it is crucial to consult a healthcare provider to rule out any underlying issues, such as iron overload or other metabolic disorders, and to ensure that the patient's iron levels, thyroid function, and other metabolic parameters are within normal ranges, as recommended in the 2022 guideline 1.
- In the meantime, maintaining healthy eating habits and regular physical activity as tolerated, and ensuring adequate hydration can help the body process the iron properly.
- It is also important to monitor iron status regularly in patients on long-term parenteral nutrition to prevent iron deficiency and iron overload, as recommended in the 2018 guideline 1.
From the Research
Potential Causes of Decreased Appetite and Weight Gain
- Decreased appetite and weight gain despite a caloric deficit following an intravenous iron infusion may be related to several factors, including:
- Hypophosphataemia, a common side effect of intravenous iron therapy, particularly with ferric carboxymaltose 2
- Changes in iron status and its effects on the body's physiological processes 3, 4
- Potential adverse effects of intravenous iron formulations, such as skin staining, infusion-related reactions, and hypophosphataemia 5
- Iron deficiency and its treatment with intravenous iron may also impact appetite and weight regulation, although the exact mechanisms are not fully understood 4, 6
- Other factors, such as pre-existing vitamin D deficiency, low calcium levels, low phosphate levels, or raised parathyroid hormone levels, may also contribute to decreased appetite and weight gain in patients receiving intravenous iron therapy 2
Relationship Between Iron Status and Appetite Regulation
- Iron deficiency has been associated with fatigue, diminished exercise capacity, and other physiological manifestations that may impact appetite and weight regulation 4
- Intravenous iron therapy may lead to improvements in iron status, but its effects on appetite and weight gain are not well established 4, 6
- Further research is needed to understand the relationship between iron status, appetite regulation, and weight gain in patients receiving intravenous iron therapy 4