What ferritin level means I am iron deficient?

Serum ferritin under 30 micrograms/L is diagnostic of iron deficiency in Australian general practice, with or without anaemia. Ferritin is an acute-phase reactant — it rises with inflammation, infection, liver disease, malignancy and obesity. If the CRP is up or there is an inflammatory condition, ferritin under 100 with a transferrin saturation under 20 percent still supports iron deficiency. Lab Tests Online AU and eTG both anchor on the under-30 threshold for primary tier diagnosis. The pre-anaemic state — iron deficiency without anaemia — is often missed when clinicians look only at haemoglobin.

Why is alternate-day iron now preferred over daily dosing?

The Stoffel trials in Lancet Haematology (2017 and 2020) showed that a single morning dose of oral iron taken every second day produces higher fractional absorption than the same dose split daily. A single dose raises hepcidin, which then blocks absorption of any further iron for around 24 hours — so splitting doses or doubling up the same day is largely wasted, and adds gastrointestinal side effects. Alternate-day dosing is now reflected in eTG and the British Society for Haematology 2021 guideline. Patients usually tolerate it better, which matters because the main reason oral iron fails is people stop taking it.

When should I have an iron infusion instead of tablets?

IV iron is appropriate when oral iron has failed despite an adequate trial, is not tolerated, cannot be absorbed (active inflammatory bowel disease, untreated coeliac disease, after bariatric surgery), or when rapid replenishment is needed — late pregnancy with severe anaemia, before major surgery, in chronic kidney disease. Ferric carboxymaltose (Ferinject) 1000 mg as a single dose is PBS Authority Required (Streamlined) for these indications. Common short-lived side effect is mild hypophosphataemia. Hypersensitivity is rare. Patients are observed for 30 minutes after infusion.

Why is my doctor asking about my bowel habits when I have low iron?

In men and post-menopausal women, unexplained iron deficiency is gastrointestinal blood loss until proven otherwise — and gastrointestinal blood loss includes bowel, gastric and oesophageal cancer. The British Society for Haematology 2021 guideline and AU primary tier both recommend gastroscopy and colonoscopy in this group, even when symptoms are absent. Premenopausal women with iron deficiency that is heavier than expected for their menstrual losses, who have a family history of bowel cancer, gastrointestinal symptoms, or are over 50, also need scoping. Coeliac serology should be done in any unexplained case.

I am pregnant — what is the iron pathway in Australia?

All pregnant women in Australia have a full blood count and ferritin at the first antenatal visit, repeated in the second and third trimesters. Oral iron is first-line, usually ferrous sulfate, alternate-day if tolerability is poor. When deficiency is severe, oral iron has failed, or the third trimester is close to delivery, ferric carboxymaltose infusion is PBS Authority Required and is the preferred IV agent. Heavy menstrual bleeding before pregnancy, vegan or vegetarian diet, short inter-pregnancy interval and multiple pregnancy all raise risk.

Can I just fix this with diet?

Diet alone rarely corrects established iron deficiency anaemia — there is simply not enough absorbable iron in food to replace what has been lost. Diet matters once stores are replenished, to prevent recurrence. Haem iron from red meat, poultry and fish is absorbed best. Plant sources — lentils, beans, tofu, fortified breakfast cereals, dark leafy greens — contain non-haem iron, which is less well absorbed but improves substantially when paired with vitamin C and separated from tea, coffee, calcium-rich foods and antacids. Vegetarians and vegans typically need more total dietary iron and benefit from a planned approach with their general practitioner or dietitian.

Iron deficiency anaemia

Iron deficiency anaemia: ferritin, alternate-day iron, and when IV is right

By Dr HB Lo, FACRRM Reviewed 19 May 2026 11 min read

Iron deficiency anaemia is the most common anaemia in Australia, with ~12–25% of menstruating women affected. Diagnosis is serum ferritin under 30 micrograms/L plus a microcytic-hypochromic full blood count.

Cause matters as much as the number. In men and post-menopausal women, unexplained iron deficiency is gastrointestinal cancer until proven otherwise. In premenopausal women, heavy menstrual bleeding leads. Always screen for coeliac disease.

Oral ferrous sulfate on alternate days is now preferred — better absorption, fewer side effects. IV ferric carboxymaltose suits oral failure, malabsorption, late pregnancy, or chronic kidney disease.

What iron deficiency anaemia actually is

Iron deficiency anaemia (IDA) is the end-state of a depletion sequence: dietary intake or absorption fails to keep up with iron loss, body iron stores empty, then haemoglobin production drops, and red blood cells become smaller (microcytic) and paler (hypochromic). Less haemoglobin means less oxygen carried per heartbeat — which is why fatigue, exertional breathlessness, hair-thinning, restless legs and brain-fog are typical presentations long before the haemoglobin reads low.

The pre-anaemic state — iron deficiency without anaemia (ID-NA) — is the part most often missed. Stores can be empty while the haemoglobin still reads normal, because the marrow strips the last of the storage iron to keep red cells in range. People feel unwell well before the full blood count looks abnormal. Anchoring only on haemoglobin lets this slip through; ferritin is the better early signal (eTG; BSH 2021).

Australian prevalence is concentrated in predictable groups: menstruating women (~12–25 percent at any time), pregnancy (rising through the second and third trimesters), vegans and vegetarians, people with occult or overt gastrointestinal bleeding, Aboriginal and Torres Strait Islander populations, endurance athletes (particularly female), frequent blood donors, and people on long-term proton pump inhibitors (HealthDirect; Lifeblood).

A. Core clinical — the AU general practice framework

RACGP clinical resources and Lab Tests Online AU describe the same general practice approach used across Australia.

How it is diagnosed

Full blood count (FBC) — anaemia is haemoglobin under 130 g/L in adult males and under 120 g/L in non-pregnant adult females. Iron deficiency anaemia is typically microcytic (MCV under 80 fL) and hypochromic (low MCH). The red cell distribution width (RDW) often rises early.
Serum ferritin — primary tier threshold is under 30 micrograms/L for iron deficiency in Australian general practice (eTG; Lab Tests Online AU). With concurrent inflammation (raised CRP, infection, liver disease, malignancy, obesity), ferritin under 100 with a transferrin saturation under 20 percent still supports iron deficiency.
Iron studies — serum iron, transferrin, transferrin saturation, total iron binding capacity. In iron deficiency, serum iron is low, transferrin is raised, saturation is under 20 percent. In anaemia of chronic disease the pattern differs — useful when ferritin is masked by inflammation.
Reticulocyte count — low or normal in iron deficiency; raised in haemolysis or acute blood loss.
CRP — to interpret a ferritin that sits in the 30–100 grey zone.

Symptoms patients describe

Fatigue, exercise intolerance, exertional breathlessness — the most common reasons for presentation.
Restless legs at night, often misdiagnosed as primary insomnia.
Hair shedding, brittle nails, koilonychia (spoon-shaped nails) in long-standing cases.
Pica — cravings for ice, dirt, paper, raw rice or starch.
Cognitive complaints: poor concentration, brain-fog, reduced exercise tolerance.
Angular cheilitis, glossitis, pallor of conjunctivae and palmar creases.
In severe chronic anaemia, tachycardia, postural symptoms and rarely high-output cardiac failure.

Symptoms can be present with normal haemoglobin if iron stores are empty — which is why a ferritin matters even when the full blood count looks fine.

B. Why? — the diagnostic workup

The iron is leaking somewhere or not coming in. Replacing iron without working out the cause is the single most common error in general practice.

Causes that drive most adult IDA

Heavy menstrual bleeding in premenopausal women — the leading cause in Australia. Pelvic assessment for fibroids, polyps and adenomyosis where indicated, plus consideration of tranexamic acid or levonorgestrel intrauterine device for ongoing management.
Gastrointestinal blood loss — peptic ulcer disease, oesophagitis, gastritis, colonic polyps, angiodysplasia, inflammatory bowel disease, and — critically — colorectal, gastric and oesophageal cancer.
Coeliac disease — present in around 5 percent of unexplained iron deficiency. Anti-tTG IgA plus a total IgA (to detect IgA deficiency) is the screen of choice (RACGP; eTG).
H. pylori infection — a common occult cause, especially in migrants and in the unexplained-deficiency group.
Chronic PPI use — reduced gastric acid impairs non-haem iron absorption.
Bariatric surgery — gastric bypass and sleeve gastrectomy reduce absorption.
NSAID use — recurrent low-grade gastrointestinal bleeding.
Frequent blood donation — more than three donations per year.
Vegan or vegetarian diet without planning.
Pregnancy, lactation, growth (adolescence), endurance training.
Returned-traveller or migrant — hookworm, schistosomiasis.

The rule that matters most

In men and post-menopausal women, unexplained iron deficiency is gastrointestinal cancer until proven otherwise. Both British Society for Haematology 2021 and AU primary tier converge: this group needs gastroscopy and colonoscopy even when bowel habits are unremarkable and there is no visible bleeding. Premenopausal women with iron deficiency disproportionate to menstrual losses, a family history of colorectal cancer, gastrointestinal symptoms, or age over 50, also need endoscopic workup.

Faecal immunochemical testing (iFOBT / FIT) is useful as adjunct while waiting for endoscopy but is not sufficient alone to exclude bowel cancer in a high-pretest-probability setting.

Workup checklist in general practice

Coeliac serology (anti-tTG IgA + total IgA)
H. pylori testing — urea breath test (MBS item 12533), faecal antigen, or gastric biopsy
Urinalysis — to exclude significant haematuria
Pregnancy test where relevant
Stool MC&S and parasites in returned travellers and migrants
Pelvic assessment in women with heavy menstrual bleeding
Endoscopy referral as above
CRP — to interpret ferritin
Renal function — chronic kidney disease commonly drives iron deficiency

C. Oral iron — alternate-day dosing changed everything

For most adults with iron deficiency anaemia, oral iron is first-line (eTG; AMH).

The dosing shift

The Stoffel trials in Lancet Haematology 2017 and Lancet Haematology 2020 demonstrated that a single oral iron dose raises plasma hepcidin for around 24 hours, which then blocks absorption of any further iron taken on the same day or the following morning. Alternate-day single dosing produces higher fractional absorption than daily or twice-daily dosing, with substantially fewer gastrointestinal side effects. This is now reflected in eTG and the BSH 2021 guideline.

What to take

The three core ferrous salts perform comparably in head-to-head studies and are all available in Australia (AMH; PBS):

Ferrous sulfate — Ferro-Gradumet (105 mg elemental iron, slow-release), Ferro-Tab (65 mg elemental), FGF (80 mg elemental).
Ferrous fumarate — Ferro-F-Tab (65 mg elemental).
Ferrous gluconate — lower elemental iron per tablet (around 35 mg), often better tolerated for sensitive patients.

TGA-listed liquid and alternative iron formulations include Maltofer (iron polymaltose) drops and tablets, FerroGrad-C (slow-release with vitamin C), Spatone (iron-rich spring water sachets, low-dose), and Ferro-Liquid (liquid ferrous sulfate, paediatric).

How to take it

One tablet on alternate days — 60–100 mg elemental iron per dose.
Take with vitamin C (a glass of orange juice or a 250 mg ascorbic acid tablet) — ascorbate reduces non-haem iron to the more absorbable ferrous form.
Avoid concurrent: tea, coffee, calcium and dairy, antacids, proton pump inhibitors and H2-receptor antagonists, quinolone and tetracycline antibiotics. Separate levothyroxine by 4 hours.
Expected response is a haemoglobin rise of around 10 g/L every 2–3 weeks. Recheck full blood count and ferritin at 3 months.
Continue for 3 months after haemoglobin normalises to replenish stores — stopping at normalisation is the second most common error.

When patients struggle

GI side effects — nausea, epigastric discomfort, constipation, dark stools, occasional diarrhoea — are the main reason oral iron fails. Strategies:

Switch from ferrous sulfate to ferrous fumarate or ferrous gluconate.
Take with food (modestly reduces absorption, often noticeably improves tolerance).
Drop to alternate-day if not already.
Trial iron polymaltose (Maltofer) — non-ionic, often better tolerated.
If three preparations have failed at adequate trial, consider IV iron.

Things to stop doing

Twice-daily oral iron — wastes the second dose on a hepcidin-blocked gut and doubles the side-effect burden.
Drinking tea or coffee with iron tablets — tannins and polyphenols precipitate iron into unabsorbable complexes. Move the brew at least an hour away from the tablet.
Stopping iron the moment the haemoglobin normalises — ferritin recovery lags haemoglobin by months. Continue at least 3 months past normalisation.
Transfusing for asymptomatic low haemoglobin — the NBA Patient Blood Management Guidelines explicitly recommend iron repletion over transfusion in non-acute settings.

D. IV iron — when and what

IV iron is genuinely useful when oral iron is not working or not appropriate (PBS; NBA Patient Blood Management Guidelines).

When IV iron is appropriate

Oral iron failure or intolerance after an adequate trial (typically 4–8 weeks of well-counselled oral therapy)
Malabsorption — active inflammatory bowel disease, untreated coeliac disease, post-bariatric surgery
Chronic kidney disease — particularly with erythropoiesis-stimulating agent support
Severe deficiency requiring rapid replenishment — pre-operative optimisation, late-pregnancy anaemia
Pregnancy in the second and third trimesters with severe anaemia or insufficient time for oral repletion
Heart failure with iron deficiency (FAIR-HF and AFFIRM-AHF data support IV iron benefit)

The agents

Ferric carboxymaltose (Ferinject) — 15 mg/kg up to 1000 mg as a single 15-minute infusion. PBS Authority Required (Streamlined). The dominant AU agent for most non-dialysis indications.
Iron polymaltose (Ferrosig / Ferrum H) — older agent, slower infusion, PBS general.
Iron sucrose (Venofer) — typically in dialysis context, PBS for chronic kidney disease.
Iron isomaltoside (Monofer) — TGA-approved single high-dose option (1000–2000 mg).

Adverse events to know

Hypophosphataemia — most often with ferric carboxymaltose, usually mild and self-limiting, occasionally prolonged or symptomatic. Check phosphate at 4 weeks if symptomatic (bone pain, weakness).
Hypersensitivity — rare (~1 in 10,000). Patients are observed for 30 minutes post-infusion. Resuscitation equipment and trained staff are available.
Skin staining at the injection site if extravasation occurs — careful infusion technique mitigates this.

The relevant MBS infusion items cover the administration in general practice settings with appropriate facilities and staff.

E. Special populations

Pregnancy

RANZCOG and NBA Patient Blood Management Module 5 (Obstetrics) recommend universal antenatal screening — full blood count and ferritin at the first antenatal visit, repeated in the second and third trimesters.

Oral ferrous sulfate is first-line. Tolerability is often worse in pregnancy than outside it — alternate-day is reasonable.
IV ferric carboxymaltose is PBS Authority for iron deficiency in pregnancy when oral has failed or is not tolerated. Increasingly used in the second and third trimesters when delivery is near.
Postpartum severe anaemia (haemoglobin under 80–90 g/L symptomatic) — IV iron is generally preferred over transfusion.
Cochrane evidence supports daily oral iron supplementation in pregnancy for prevention of maternal anaemia and improved birthweight outcomes.

Heavy menstrual bleeding

Treating the iron and ignoring the bleeding sets up a cycle. Options for the underlying menorrhagia include tranexamic acid (typically 1 g three to four times daily during the heaviest days), levonorgestrel intrauterine device (the most effective hormonal option for heavy menstrual bleeding), combined hormonal contraception, oral or injectable progestogens, and surgical options (endometrial ablation, myomectomy, hysterectomy) where conservative measures fail. RACGP and RANZCOG resources cover the full pathway.

Aboriginal and Torres Strait Islander populations

Higher background prevalence in many Aboriginal and Torres Strait Islander communities. The MBS item 715 (Aboriginal and Torres Strait Islander Health Assessment) is the appropriate vehicle for systematic screening and care planning.

Vegetarian and vegan diet

Iron-rich plant foods — lentils, beans, chickpeas, tofu, fortified breakfast cereals, dark leafy greens, pumpkin seeds, quinoa — paired with vitamin C and separated from tea, coffee, and calcium-containing foods. NHMRC Eat for Health provides the canonical AU dietary framework. Co-existing B12 and zinc deficiency should be considered.

Endurance athletes

Particularly female endurance athletes. Ferritin targets are often higher (typically 50–75 micrograms/L for symptom resolution rather than the under-30 deficiency threshold). Mechanisms include foot-strike haemolysis, hepcidin elevation from inflammation, sweat losses, and dietary inadequacy.

Paediatric

Common at 9–18 months and again at adolescence. Iron-fortified formula and cereals, iron-rich complementary foods from 6 months, and consideration of vitamin D. Paediatric dosing is 3 mg/kg/day elemental iron. Liquid forms — Ferro-Liquid (ferrous sulfate) and Maltofer (iron polymaltose) — are used; Maltofer has a tolerability advantage in toddlers, ferrous sulfate has the stronger evidence base for nutritional iron deficiency anaemia. Choose by tolerability and adherence; reasonable to start with Maltofer drops where tooth-staining is a concern, switch to ferrous sulfate if haemoglobin response is inadequate at 4 weeks.

Chronic kidney disease

Iron deficiency is common in chronic kidney disease and combines with reduced erythropoietin production. IV iron is preferred over oral; erythropoiesis-stimulating agents are added under nephrology guidance.

When to escalate

Refer or escalate when:

Iron deficiency anaemia remains refractory despite optimised oral or IV iron and treatment of identified causes
Adult unexplained iron deficiency warranting gastroscopy and colonoscopy
Suspected gastrointestinal, gynaecological or urological malignancy
Pregnancy with severe or refractory anaemia, or delivery approaching with low haemoglobin
Chronic kidney disease anaemia
Suspected concurrent haemolysis or other haematological disorder
Bariatric or complex dietary patient needing structured dietetic input
Symptomatic restless legs not responding to iron repletion at a ferritin target above 75 micrograms/L

What this article is and is not

This is general health information drawn from current Australian general practice tier guidance — Therapeutic Guidelines, RACGP clinical resources, the Australian Medicines Handbook, NPS MedicineWise, Lab Tests Online AU, the National Blood Authority Patient Blood Management Guidelines, RANZCOG and Lifeblood — alongside major peer-reviewed trials. It is not personal medical advice and does not create a doctor–patient relationship. Decisions about specific investigation and treatment — including endoscopy referral, IV iron, and management in pregnancy — are made with your own general practitioner and treating clinicians.

For Australian consumer-friendly sources: HealthDirect — Iron deficiency, Better Health Channel — Iron, Lab Tests Online AU, NHMRC Eat for Health, Australian Red Cross Lifeblood.

Sources cited

Frequently asked questions

What ferritin level means I am iron deficient?

Serum ferritin under 30 micrograms/L is diagnostic of iron deficiency in Australian general practice, with or without anaemia. Ferritin is an acute-phase reactant — it rises with inflammation, infection, liver disease, malignancy and obesity. If the CRP is up or there is an inflammatory condition, ferritin under 100 with a transferrin saturation under 20 percent still supports iron deficiency. Lab Tests Online AU and eTG both anchor on the under-30 threshold for primary tier diagnosis. The pre-anaemic state — iron deficiency without anaemia — is often missed when clinicians look only at haemoglobin.
Why is alternate-day iron now preferred over daily dosing?

The Stoffel trials in Lancet Haematology (2017 and 2020) showed that a single morning dose of oral iron taken every second day produces higher fractional absorption than the same dose split daily. A single dose raises hepcidin, which then blocks absorption of any further iron for around 24 hours — so splitting doses or doubling up the same day is largely wasted, and adds gastrointestinal side effects. Alternate-day dosing is now reflected in eTG and the British Society for Haematology 2021 guideline. Patients usually tolerate it better, which matters because the main reason oral iron fails is people stop taking it.
When should I have an iron infusion instead of tablets?

IV iron is appropriate when oral iron has failed despite an adequate trial, is not tolerated, cannot be absorbed (active inflammatory bowel disease, untreated coeliac disease, after bariatric surgery), or when rapid replenishment is needed — late pregnancy with severe anaemia, before major surgery, in chronic kidney disease. Ferric carboxymaltose (Ferinject) 1000 mg as a single dose is PBS Authority Required (Streamlined) for these indications. Common short-lived side effect is mild hypophosphataemia. Hypersensitivity is rare. Patients are observed for 30 minutes after infusion.
Why is my doctor asking about my bowel habits when I have low iron?

In men and post-menopausal women, unexplained iron deficiency is gastrointestinal blood loss until proven otherwise — and gastrointestinal blood loss includes bowel, gastric and oesophageal cancer. The British Society for Haematology 2021 guideline and AU primary tier both recommend gastroscopy and colonoscopy in this group, even when symptoms are absent. Premenopausal women with iron deficiency that is heavier than expected for their menstrual losses, who have a family history of bowel cancer, gastrointestinal symptoms, or are over 50, also need scoping. Coeliac serology should be done in any unexplained case.
I am pregnant — what is the iron pathway in Australia?

All pregnant women in Australia have a full blood count and ferritin at the first antenatal visit, repeated in the second and third trimesters. Oral iron is first-line, usually ferrous sulfate, alternate-day if tolerability is poor. When deficiency is severe, oral iron has failed, or the third trimester is close to delivery, ferric carboxymaltose infusion is PBS Authority Required and is the preferred IV agent. Heavy menstrual bleeding before pregnancy, vegan or vegetarian diet, short inter-pregnancy interval and multiple pregnancy all raise risk.
Can I just fix this with diet?

Diet alone rarely corrects established iron deficiency anaemia — there is simply not enough absorbable iron in food to replace what has been lost. Diet matters once stores are replenished, to prevent recurrence. Haem iron from red meat, poultry and fish is absorbed best. Plant sources — lentils, beans, tofu, fortified breakfast cereals, dark leafy greens — contain non-haem iron, which is less well absorbed but improves substantially when paired with vitamin C and separated from tea, coffee, calcium-rich foods and antacids. Vegetarians and vegans typically need more total dietary iron and benefit from a planned approach with their general practitioner or dietitian.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.