IV iron: Is it always the right prescription?

IV iron involves administering iron directly into the bloodstream through a vein. This bypasses the digestive system and allows a relatively large amount of iron to be delivered in a single treatment or a small number of treatments. Sounds pretty good right!?

There are several forms of IV iron available in Australia. One of the most commonly used is ferric carboxymaltose, sold under the brand name Ferinject, as well as a number of generic products.

You may sense my sarcasm... but don't get me wrong. There are certainly times when IV iron

is a very useful treatment.... BUT my experience is that oftentimes it is overprescribed and viewed as an 'easier' quick fix to correct low iron and hence we are seeing an increase in adverse reactions

When is ferric carboxymaltose indicated in Australia?

According to the Australian Therapeutic Goods Administration (TGA), ferric carboxymaltose is indicated for the treatment of iron deficiency in adults and adolescents aged 14 years and older when:

• oral iron preparations are ineffective

• oral iron preparations cannot be used

• there is a clinical need to deliver iron rapidly.

So an IV iron infusion isn't simply a treatment for "feeling tired" or for a ferritin number that happens to be on the lower side.

There should be evidence of iron deficiency and a reason why intravenous iron is the appropriate way to treat it.

But IV iron isn't risk-free

Because IV iron bypasses the body's normal digestive and absorption processes and delivers a large amount of iron directly into the circulation, there are potential risks.

One of the most important — and sometimes overlooked — risks with ferric carboxymaltose is hypophosphataemia, meaning a drop in blood phosphate.

This is often mild and temporary, but in some people it can be significant. Severe or persistent hypophosphataemia can cause fatigue, weakness, muscle symptoms and bone pain and, in prolonged cases, can contribute to problems with bone mineralisation.

Interestingly, the symptoms of hypophosphataemia can look very similar to the symptoms someone was hoping the iron infusion would fix — fatigue, weakness, breathlessness and headaches. The TGA specifically advises considering hypophosphataemia when symptoms continue after ferric carboxymaltose treatment.

The risk is particularly relevant when people require repeated or high-dose treatment, and certain factors can increase susceptibility.

Other potential risks of IV iron include hypersensitivity reactions, including rare serious allergic reactions, changes in blood pressure and reactions at the infusion site. If iron leaks outside the vein during administration (extravasation), it can also cause persistent skin discolouration.

And, as with any treatment, giving more iron than the body actually needs is not without consequences. Excessive administration can result in iron accumulation, which is why iron status should be appropriately assessed and monitored.

So, should you have an iron infusion?

IV iron can be an incredibly useful treatment and, for some people, it is absolutely appropriate.

But I think it's worth stepping back from the idea that a low ferritin automatically means an iron infusion is the answer.

Before treating iron deficiency, I want to know why the iron is low in the first place.

Is there ongoing blood loss? Is iron being adequately absorbed? Is there a dietary insufficiency? Is there an underlying gastrointestinal issue? Has oral iron actually been tried appropriately and tolerated? Is there inflammation affecting iron metabolism? And importantly — is there clear evidence of iron deficiency on the appropriate laboratory tests?

Because correcting the number is only part of the story.

The question isn't just "Is your ferritin low?"

It's "Do you actually have iron deficiency, why is it happening, and does the benefit of IV iron outweigh the risks for you?"

That is a much more useful conversation to have before reaching for the IV.