Medical uses
Iron supplements are used to treat iron deficiency and iron-deficiency anemia; parenteral irons can also be used to treat functional iron deficiency, where requirements for iron are greater than the bodys ability to supply iron such as in inflammatory states. The main criterion is that other causes of anemia have also been investigated, such as vitamin B12 or folate deficiency, drug induced or due to other poisons such as lead, as often the anemia has more than one underlying cause. Iron deficiency anemia is classically a microcytic, hypochromic anemia. Generally, in the UK oral preparations are trialled before using parenteral delivery, unless there is the requirement for a rapid response, previous intolerance to oral iron or likely failure to respond. Intravenous iron may decrease the need for blood transfusions however it increases the risk of infections when compared to oral iron. A 2015 Cochrane Collaboration review found that daily oral supplementation of iron during pregnancy reduces the risk of maternal anemia and that effects on infant and on other maternal outcomes are not clear. Another review found tentative evidence that intermittent iron supplements by mouth for mothers and babies is similar to daily supplementation with fewer side effects. Supplements by mouth should be taken on an empty stomach, optionally with a small amount of food to reduce discomfort. Athletes
Athletes may be at elevated risk of iron deficiency and so benefit from supplementation, but the circumstances vary between individuals and dosage should be based on tested ferritin levels, since in some cases supplementation may be harmful.
Parenteral therapy is more expensive than oral iron preparations and is not suitable during the first trimester of pregnancy.There are cases where parenteral iron is preferable over oral iron. These are cases where oral iron is not tolerated, where the haemoglobin needs to be increased quickly (e.g. post partum, post operatively, post transfusion), where there is an underlying inflammatory condition (e.g. inflammatory bowel disease) or renal patients, the benefits of parenteral iron far outweigh the risks. In many cases, use of intravenous iron such as ferric carboxymaltose has lower risks of adverse events than a blood transfusion and as long as the person is stable is a better alternative. Ultimately this always remains a clinical decision based on local guidelines, although National Guidelines are increasingly stipulating IV iron in certain groups of patients.Soluble iron salts have a significant risk of adverse effects and can cause toxicity due to damage to cellular macromolecules. Delivering iron parenterally has utilised various different molecules to limit this. This has included dextrans, sucrose, carboxymaltose and more recently Isomaltoside 1000.One formulation of parenteral iron is iron dextran which covers the old high molecular weight (trade name DexFerrum) and the much safer low molecular iron dextrans (tradenames including Cosmofer and Infed).Iron sucrose has an occurrence of allergic reactions of less than 1 in 1000. A common side effect is taste changes, especially a metallic taste, occurring in between 1 in 10 and 1 in 100 treated patients.