How do I calculate the Ferinject dose?

There are two methods. The Simplified method uses a table based on weight and Hb: for patients under 70kg with Hb under 100, give 1500mg total; Hb 100-140 give 1000mg; Hb 140 or over give 500mg. For patients 70kg or over, give 2000mg, 1500mg, or 500mg respectively. For iron deficiency with a normal Hb (low ferritin only), give 500mg under 70kg or 1000mg at 70kg or over. The Ganzoni formula is more precise: total iron (mg) = weight × (target Hb - actual Hb) × 0.24 + 500. Maximum single dose is 20mg/kg capped at 1000mg per week.

What MBS item do I bill for an iron infusion?

There is currently no specific MBS item for iron infusions in general practice. The RACGP is advocating for a dedicated item but one does not yet exist. In practice, GPs bill a standard time-based consultation item (23, 36, or 44) for the clinical assessment, and privately charge a separate procedure fee for the infusion itself (typically $100-$200 for consumables, nursing time, and monitoring). The drug (Ferinject or Monofer) is PBS-covered separately. Check with your practice manager and local PHN for current billing guidance.

👩‍⚕️ Clinical reference for health professionals. This page summarises published clinical guidance and is not medical advice. Patients and members of the public: please don’t use this to make decisions about your own care — talk to your GP, pharmacist or treating team.

Iron Infusion Dosing & Billing

Ferinject and Monofer dosing calculator. Dose, vials, sessions, and MBS items.

📋 Sources: Patel S. “Ferric carboxymaltose: A practical guide on the administration of iron infusions in general practice.” AJGP 2025;54(5) — racgp.org.au/ajgp (erratum September 2025). Ganzoni formula for iron deficit calculation. Ferinject (ferric carboxymaltose) and Monofer (ferric derisomaltose) dosing per TGA-approved Product Information. National Blood Authority Australia — iron product choice and dose calculation guide — blood.gov.au. PBS codes 3557 (Ferinject) and 14081 (Monofer). Note: there is currently no specific MBS item for iron infusion administration in GP — billing is via standard consultation items + private procedure fee. Always confirm dosing with the current PI and local guidelines. Clinical judgement applies.

Patient context

⚠ Ferinject max single dose: 20 mg/kg body weight, capped at 1,000 mg per week. Minimum 7 days between doses. Always confirm with the current Ferinject PI.

Simplified dosing table (adults ≥35 kg)

Body weight (kg)

Haemoglobin (g/L)

Indication

Iron deficiency anaemia (low Hb) Iron deficiency only (normal Hb, low ferritin)

Simplified dosing reference

Hb (g/L)

35–<70 kg

≥70 kg

Normal Hb, low ferritin

500 mg

1,000 mg

<100

1,500 mg

2,000 mg

100–<140

1,000 mg

1,500 mg

≥140

500 mg

Source: Ferinject Product Information (TGA-approved). Max cumulative dose per the table. Max 1,000 mg per week.

Ganzoni formula

Total iron (mg) = weight (kg) × (target Hb − actual Hb) × 0.24 + iron stores

Body weight (kg)

Actual Hb (g/L)

Target Hb (g/L)

140 g/L for adults ≥35kg, 130 g/L for <35kg

Iron stores (mg)

500 mg for ≥35kg, 15 mg/kg for <35kg

Billing for Iron Infusions in GP

⚠ No specific MBS item exists for iron infusions in GP. The RACGP is advocating for a dedicated item ($200 proposed) but it has not been approved. Do not bill item 13915 for iron infusions — this item has specific descriptor requirements that may not apply and carries audit risk.

How most GP practices bill (current practice):

1️⃣Consultation item (MBS) — bill a standard time-based item (23, 36, or 44) for the clinical assessment: reviewing bloods, calculating dose, discussing risks, obtaining consent. This is the Medicare-rebatable component. 2️⃣Private procedure fee (non-MBS) — charge a separate fee for the infusion procedure itself: nursing time, consumables, IV setup, 30-minute observation. Typically $100–$200. This is not Medicare-rebatable and the patient pays out-of-pocket. 3️⃣PBS prescription — the drug (Ferinject or Monofer) is prescribed under the PBS. The patient fills the script at a pharmacy or the practice purchases stock. PBS-covered cost: ~$25.00 general / ~$7.70 concession.

Alternative: Some practices fully privately bill the entire service (no MBS consultation item) with a single fee covering everything. Typical total cost to patient: $200–$400 including drug.

Under BBPIP: If you bulk bill the consultation (item 23/36), the iron infusion procedure fee must also be bulk billed (NRA items). Some practices choose to fully privately bill to avoid this restriction.

PBS scripts:

Ferinject is PBS Authority Required (Streamlined) for iron deficiency anaemia where oral iron is not tolerated, ineffective, or inappropriate. Code 3557.

Vial sizes available:

Ferinject: 100 mg/2 mL and 500 mg/10 mL. Single use only — discard any unused portion. PBS covers the cost to the patient ($25.00 general / $7.70 concession).

Billing guidance varies — always check with your practice manager and local PHN. Billing Conflict Checker →

Ferinject:

IV infusion (preferred for doses >200mg): Dilute in 0.9% NaCl — 500mg in 100mL or 1000mg in 250mL. Infuse over 15-30 minutes.

IV injection (doses ≤200mg): Undiluted, give at max 50mg/min. Rarely used in GP.

Minimum dilution: Do not dilute below 2mg iron/mL.

Monofer:

≤1000mg: Dilute in 100mL 0.9% NaCl. Infuse over 15-30 minutes.

>1000mg (up to 20mg/kg): Dilute in 250-500mL 0.9% NaCl. Infuse over 30-60 minutes.

IV injection (≤500mg): Undiluted at max 50mg/min. Can give 500mg in 10 minutes.

Key difference: Monofer has no weekly cap — full dose can often be given in one session (up to 20mg/kg). Ferinject is capped at 1000mg per session with 7 days between doses.

Monitoring (both): BP, pulse, temperature, and respiratory rate during and for 30 minutes post-infusion. Document observations. Resuscitation equipment must be available.

Ferinject can be given from the second trimester onwards (after 13 weeks, many clinics wait until 16 weeks).

Max dose in pregnancy: 20mg/kg, capped at 1,000mg per week. Use the Ganzoni formula with target Hb 110 g/L (per UK/RANZCOG guidelines) or 140 g/L (per Ferinject PI). Max cumulative dose: 1,000mg if Hb >90, 1,500mg if Hb ≤90. From 2nd trimester only (≥16 weeks). Discuss with local guidelines.

Contraindicated in first trimester. For severe anaemia in first trimester, consider oral iron or blood transfusion.

Use pre-pregnancy weight for dose calculation if significantly different from current weight.

Ferinject can cause hypophosphataemia, usually transient and asymptomatic. However, with repeated doses it can cause clinically significant phosphate depletion leading to osteomalacia.

Higher risk: Vitamin D deficiency, IBD, malabsorption, secondary hyperparathyroidism, repeated Ferinject courses.

Check phosphate if giving repeated infusions, patient has risk factors, or symptoms of bone pain / muscle weakness develop.

Monofer advantage: Ferric derisomaltose (Monofer) has a significantly lower risk of hypophosphataemia compared to ferric carboxymaltose (Ferinject). Consider Monofer for patients needing repeated courses, those with vitamin D deficiency, or those with previous hypophosphataemia on Ferinject.