The down low on iron infusions

Iron deficiency is one of the more common nutritional deficiencies in Australia.¹ Anaemia affects roughly 15% of non-pregnant premenopausal women, 12% of pregnant women, and about 8% of children under five.²

The symptoms are easy to put down to something else. Ongoing tiredness, breathlessness on exertion, poor concentration, hair shedding, headaches, restless legs, pale skin. None of them points only to iron deficiency, which is why diagnosis relies on a blood test.

Intravenous iron (given into a vein by infusion) has become more common in Australian general practice over the past decade, in part because newer formulations can deliver a full replacement dose in a single short appointment.³However, rushing into an iron infusion is not the first course of action. If you have had pathology results revealing you are low in iron, your GP will generally want to establish why before deciding how to treat it.

• Iron deficiency is common in Australia and it is treatable.
• A blood test is the best diagnostic tool for low iron.
• Increasing dietary sources of iron always comes first, then tablet supplements.
• Infusions are for when those have not worked or will not work fast enough.
• Infusions carry more risk, including a risk of permanent skin staining.

Low iron and anaemia are not the same thing

You can be iron deficient without being anaemic. Iron deficiency comes first, and anaemia is what happens when the deficiency has gone on long enough to affect your red blood cells. You can sit in that earlier stage, feeling flat, with a haemoglobin still inside the normal range.

The blood test

Ferritin is often tested as part of a routine check on iron levels; it reflects how much iron your body has in storage. Australian Red Cross Lifeblood describes ferritin as the diagnostic test of choice and defines iron deficiency in adults as a ferritin below 30 micrograms per litre.⁴

Serum iron is often also tested during when measuring iron levels, Lifeblood advises that serum iron should not be the key indicator used to diagnose iron deficiency, because it reflects recent dietary intake rather than stored iron.⁴

A normal ferritin level does not always rule out low iron. Ferritin is an acute phase protein, meaning it rises during inflammation, infection, liver disease and some cancers. Someone who is genuinely iron deficient but also has an inflammatory condition can show a ferritin as high as 100 and still be deficient.⁴ Your GP may therefore also look at transferrin saturation, a full blood count, and a marker of inflammation such as CRP, rather than treating one number in isolation.

Why your GP will want to find the cause first

Establishing the cause shapes the treatment.

Iron deficiency is a finding rather than a diagnosis. It means iron is either not going in, not being absorbed, or being lost somewhere. An infusion restores the stores without answering which of those it is.

Australian guidance recommends that everyone with confirmed iron deficiency anaemia (where the blood level or haemoglobin has dropped) has a urine test and is screened for coeliac disease.⁵ This is best discussed with your GP. What happens beyond that depends on your situation:

• In younger women, menstrual losses, pregnancy and diet are the usual explanations, and underlying gut disease is less common. After coeliac screening, further investigation is generally reserved for those with additional concerns: age over 50, no longer menstruating, red flag gut symptoms, a strong family history of bowel cancer, or deficiency that keeps coming back despite treatment.⁵
• In adult men and women past menopause, bleeding from the gut is the most common cause, and gastroscopy and colonoscopy are generally the first investigations recommended.⁵

Correcting the deficiency without establishing the cause can mean the symptoms improve while the reason for them goes unnoticed, and occasionally that reason needs treating in its own right.

In most people the cause is straightforward: heavy periods, pregnancy, a diet low in iron, coeliac disease, or a medication that reduces absorption.

Diet: where treatment starts

Your GP will usually review what you are eating. Dietary intake is both a possible cause of low iron and part of the treatment.

There are two kinds of iron in food. Haem iron comes from animal sources such as red meat, poultry and fish, and the body absorbs it readily. Non-haem iron comes from plants, eggs and nuts, and is harder to absorb. Dietitians Australia notes that most of the iron in the Australian diet actually comes from plant-based foods, even for people who eat meat.⁶

How much you need depends on who you are. The Australian recommended dietary intakes are 18 mg a day for women aged 19 to 50, 8 mg a day for men and for women over 50, 27 mg during pregnancy and 9 mg while breastfeeding.⁷

How much you absorb matters as much as how much you eat. A mixed diet including animal foods delivers roughly 18% of its iron into the body. A vegetarian diet delivers around 10%, which is why vegetarians may need close to twice as much dietary iron.⁸

What helps absorption

• Vitamin C at the same meal. Citrus, tomatoes, capsicum, broccoli, strawberries.⁶
• Eating meat, fish or poultry alongside plant sources, which lifts absorption from the plant foods as well⁷
• Cooking plant foods rather than eating them raw⁹

What gets in the way

• Tea, coffee and red wine with meals. Dietitians Australia advises keeping these away from mealtimes rather than giving them up⁶.
• Calcium rich foods and calcium supplements taken alongside a meal⁶
• Phytates, found in legumes, rice and wholegrains. Timing and variety matter more than avoiding these foods, which are valuable for other reasons⁷

Timing matters as much as content. The same meal with orange juice rather than tea delivers a different amount of absorbed iron.

Where diet stops being enough. If your stores are already depleted, dietary change alone will usually not rebuild them at a useful rate, and where there is ongoing blood loss it will struggle to keep pace. Supplements are generally the next step. If your situation is more complicated, for example if you are vegetarian or vegan or have a condition affecting absorption, an Accredited Practising Dietitian can give you advice specific to you.⁶

Iron supplementation

Where dietary changes are not enough on their own, oral iron is the appropriate treatment for most people.³ It is inexpensive, it does not need a cannula, and when it is absorbed and tolerated, it can rebuild your stores fully.

Side effects are the main reason it does not work out. Constipation, nausea and stomach upset are common, and some people stop early because of them. Two things can help. Taking a lower dose, or taking it every second day rather than daily, tends to improve both absorption and tolerability. Rebuilding stores takes months rather than weeks, and stopping once you feel better can see the deficiency return.

If tablets genuinely have not worked, or you cannot tolerate them, or you need iron restored quickly, that is when an infusion is worth discussing with your GP.³

When an infusion is the right call

Intravenous iron is generally considered when:

• oral iron has been tried properly and has not worked
• the side effects of tablets are genuinely intolerable
• iron needs to be replaced quickly, such as later in pregnancy or before surgery
• there is a problem with absorption, for example in uncontrolled coeliac disease or after some types of bowel surgery
• ongoing blood loss means tablets cannot keep up

In these circumstances, intravenous iron is the appropriate way to replace it.

What happens on the day

A cannula is placed into a vein, usually in the arm, and the iron is given through it. Depending on the preparation and the dose, this generally takes between fifteen minutes and half an hour.

You are then observed for at least thirty minutes afterwards by clinical staff. It is recommended that you plan to be at the clinic for around an hour in total. The staff will monitor you during this time and ask you to tell them if you feel any pain, burning, stinging or swelling around the cannula at any point.

Side effects and risks

There are, in most cases, no side effects, though some may notice a metallic taste, flushing, headache, nausea or aching at the insertion point for the infusion for a day or two. Some more concerning side effects can be:

Skin staining

If iron leaks out of the vein into the surrounding tissue during the infusion, it can leave a brown or black mark on the skin. This is sometimes called an iron tattoo. It can happen even when the infusion is performed carefully and correctly, and it is often permanent.¹¹

This is why staff ask you to tell them straight away if anything feels wrong at the cannula site, rather than waiting to see whether it settles. The risk is also covered as part of the consent conversation before the infusion begins.

Low phosphate

One of the intravenous iron preparations used in Australia, ferric carboxymaltose, can lower the phosphate level in your blood. The TGA has issued a safety update on this.¹³

Low phosphate causes fatigue, weakness, breathlessness and headaches, which are also symptoms of iron deficiency. If you still feel unwell some days or weeks after an infusion, that can be mistaken for the treatment not having worked. It is usually treated with phosphate supplements, and it usually resolves.

If your symptoms have not improved a couple of weeks after an infusion, contact your practice.

Allergic reactions

Serious anaphylactic allergic reactions to intravenous iron are uncommon but possible, which is the reason for the observation period and the trained staff.¹⁰ Tell your GP beforehand if you have had a reaction to an iron infusion in the past, or if you have significant allergies generally.

Will it lift my iron levels?

Yes, in most cases. Restoring iron stores is what intravenous iron does reliably, and it is the reason it is used when levels need to come up quickly or when tablets have not worked.

Whether that resolves how you have been feeling is a slightly different question, and it depends on whether iron deficiency was the cause, and how your body reacts. 

Next steps

If you have had a blood test that shows your ferritin is low, the next step is usually a conversation with your GP about why and how to treat it. The two questions get worked through together. In most people the cause turns out to be something straightforward, but that is a conclusion reached after looking rather than before.

If tablets have not agreed with you, say so rather than stopping quietly. There are ways to make oral iron easier to tolerate, and if those do not work, an infusion is a reasonable discussion point with your GP as a possible next step.

Iron deficiency is common and it is treatable.

To have your iron levels checked or to discuss treatment options, book an appointment with your local Qualitas Medical Practice GP.

This article is general information only and is not a substitute for individual medical advice. Speak with your GP about your own circumstances.

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