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Updated: Jan 29, 2020

Traditionally, oral iron is usually prescribed as a first line treatment of iron deficiency with or without anaemia.

In order to achieve the best absorption rates of oral iron with the lowest rates of side effects, it is recommended to take tablets on alternate days on an empty stomach and without any other medications. Unfortunately, most oral iron supplements will have their absorption impaired by food - tea can even further impair absorption by up to 90%.

Oral iron is often recommended with vitamin C - is that always required? The addition of vitamin C to oral iron supplements is probably not necessary. In fact, there is a chance that this will increase common GI side effects.

The most commonly used (and cheapest) iron supplements are ferrous salts (e.g., ferrous sulfate or ferrous fumerate). The ferrous (or Fe2+) form of iron is absorbed by the body in both a controlled and uncontrolled manner. It is this uncontrolled uptake that can lead to oversaturation of the iron transfer system and lead to unwanted side effects such as nausea, constipation or diarrhoea plus continued unregulated use could potentially lead to iron overload. Just to make things worse, ferrous iron formulations have a rust or blood like taste further decreasing most people’s desire to take routinely and for the required, many months.

At The Iron Suites we prescribe ferric (Fe3+) iron compounds which are absorbed via a controlled manner (similar to the iron from food) and not the uncontrolled manner. Clinical trials with ferric iron compounds have shown significantly fewer GI related side effects.

Additionally, they have the benefit of being able to be taken with food or other supplements (meaning you can take them any time of the day) as well as often having a preferable taste.

The other reason for our preference for the ferric form of iron is the very low chance of overdosing. For instance, if 30 tablets of ferrous sulfate or ferrous fumerate were accidentally ingested by you or your child there would be a very high risk of severe or even fatal outcomes (due to the uncontrolled absorption) whilst the ferric forms will pass straight through with very low (if any) risk for toxicity.

Independent of the oral iron formulation used, the response after commencing should be checked. Not everyone will be able to absorb supplements to the degree needed to correct iron deficiency. Checking after ~1 month is important for iron deficient anaemic patients and ideally an increase of at least 1g/dl should be observed. For the patient with iron deficiency (and normal Hb levels), we aim to see an increase in ferritin from baseline and ideally a concentration of greater than 30ng/mL after 3 months of continuous use.

To help understand the above timing for re-assessments, an increase in Haemoglobin (Hb) by 1 point (i.e., from 11 to 12) needs ~200mg iron and after Hb is corrected, the iron stores (measured by serum ferritin), need ~8mg to increase by 1 points (i.e., to increase from a ferritin of 10 to 20ng/mL will require ~80mg iron). The average woman loses ~2mg iron per day and with oral iron (or even an optimised diet) combined with optimised absorption the iron intake may reach ~10-15mg iron per day (or ~200-300mg per month).

This is why we like to see at least 1g/dL increase in Hb by 1 month. Once Hb is normalised, then the iron should be going to the stores (as long as it is being absorbed) and that is why we look at ferritin at ~3 months.

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