CKD anemia content reviewed November 6, 2026 against KDIGO 2026. Population-specific rules are in the Evidence section below and in the CKD anemia guide.
- Select conventional (g/dL) or SI (g/L) units.
- Enter positive body weight, current Hb, and a clinician-selected target above current Hb.
- Choose route and an individualized storage allowance; 500 mg is a common adult estimate.
- Read the estimated deficit. For 60 kg and Hb 8→11 g/dL with 500 mg storage: 932 mg. This estimate does not establish treatment eligibility.
When to use
Use after iron therapy has already been judged appropriate (see the TSAT & ferritin calculator) to estimate the cumulative amount of IV iron an adult needs. The Ganzoni equation sizes the dose; it does not decide whether iron is indicated.
- Adults with CKD (including dialysis) and confirmed iron deficiency who are starting a course of IV iron.
- Not for children, for deciding eligibility, or for maintenance dosing in hemodialysis, which follows a proactive schedule rather than a one-time deficit.
Interpretation and limitations
- Units matter: the factor is 2.4 with Hb in g/dL, or 0.24 with Hb in g/L.
- Body weight: use post-dialysis dry weight in HD and ideal body weight in obesity, as IV iron product labels advise.
- Storage allowance: 500 mg is typical for adults ≥35 kg; about 15 mg/kg below 35 kg. Reduce it if stores were recently repleted.
- Ongoing losses are not included: HD circuit losses, GI bleeding, or frequent phlebotomy make the estimate an underestimate.
- Dose limits: never exceed the maximum single dose of the chosen product (KDIGO 2026 practice point 2.9); split the total accordingly.
- Target Hb: a calculation assumption only. For adults on ESA, the maintenance goal is below 11.5 g/dL.
Why Use It
Iron deficiency is the most common correctable cause of anemia in CKD, affecting over 60% of predialysis patients and nearly all hemodialysis patients. Adequate iron stores are a prerequisite for the erythropoietic response to ESA therapy — without iron repletion, ESA doses escalate, costs rise, and hyporesponsiveness persists. The Ganzoni equation converts the hemoglobin gap and body weight into a total iron dose that accounts for both the circulating hemoglobin-bound iron deficit and a 500 mg depot reserve for bone marrow stores.
In hemodialysis patients, IV iron sucrose (iron sucrose — marketed as Ferrofer in the Philippines) is preferred over oral iron because intestinal absorption is severely impaired by hepcidin upregulation. IV iron delivered into the dialysis venous return line at 100–200 mg per session avoids gastrointestinal intolerance and achieves reliable tissue loading. KDIGO 2026 suggests IV rather than oral iron in hemodialysis when ferritin is ≤500 ng/mL and TSAT ≤30%, supports a proactive, monitored regimen similar to the PIVOTAL trial, and advises withholding routine iron when ferritin exceeds 700 ng/mL or TSAT reaches 40%.
Iron Deficit & IV Iron Dose — Ganzoni Equation
Enter body weight, current hemoglobin, target hemoglobin, and the intended route of iron replacement to calculate total iron deficit and infusion sessions.
Ganzoni estimate (mg) = weight (kg) × Hb gap (g/dL) × 2.4 + the selected storage allowance (mg). With Hb in g/L, use 0.24 instead. A 500-mg storage allowance is a common adult estimate; individualize it for body size and prior replacement. This is a deficit estimate, not an automatic repletion or maintenance prescription.
Next steps
- Split the estimate into doses allowed by the product label (for example, iron sucrose 100–200 mg per HD session).
- Hold the course during systemic infection, and stop if ferritin exceeds 700 ng/mL or TSAT reaches 40%.
- Recheck Hb, ferritin, and TSAT after the course. Allow at least 1–2 weeks after iron sucrose and about 4 weeks after a large single dose, because recent IV iron transiently raises both indices.
- If Hb does not respond despite adequate iron, evaluate other causes and ESA hyporesponsiveness (ERI calculator).
Evidence and clinical rules
| Population / decision | KDIGO 2026 guidance |
|---|---|
| Anemia + hemodialysis (HD): initiate iron | Ferritin ≤500 ng/mL and TSAT ≤30%. IV iron is suggested; use a proactive, monitored approach. |
| Anemia + non-dialysis CKD or peritoneal dialysis (PD): initiate iron | Ferritin <100 ng/mL and TSAT <40%, or ferritin ≥100 and <300 ng/mL and TSAT <25%. |
| Route outside HD | Choose oral or IV iron using severity, response, tolerance, preference, availability, and cost. Switch an optimal oral regimen to IV if ineffective after 1–3 months or poorly tolerated. |
| Withhold routine iron | Ferritin >700 ng/mL or TSAT ≥40%. An elevated ferritin alone does not diagnose iron overload. |
| Systemic infection | Consider temporarily suspending iron. Inflammation without infection needs clinical assessment rather than an automatic infection diagnosis. |
| Ganzoni equation | Deficit (mg) = weight (kg) × (target Hb − actual Hb, g/dL) × 2.4 + storage iron (mg). Storage iron 500 mg if ≥35 kg; about 15 mg/kg if <35 kg (Ganzoni 1970; IV iron product labels). |
| Profound iron deficiency without anemia | Ferritin <30 ng/mL and TSAT <20%: consider oral or IV iron, especially with symptoms (practice point 2.11). |
| Kidney transplant recipients | KDIGO 2026 applies the non-dialysis criteria (Appendix Figure 4). Monitor phosphate after ferric carboxymaltose and similar preparations. |
| Monitoring during iron treatment | Hb, ferritin, TSAT every 3 months in non-dialysis CKD/PD; every 1–3 months in HD, often monthly. Test sooner after blood loss, hospitalization, ESA escalation, or rapidly changing iron indices. |
For ESA decisions, the adult maintenance Hb goal is below 11.5 g/dL (115 g/L); see the ESA dose calculator.
Source: KDIGO 2026 Anemia in CKD, recommendations 2.1–2.4 and 3.2.1–3.3.1; practice points 2.2–2.8 and 3.4.1.2–3.4.3.5. Reviewed November 6, 2026. Apply clinical judgment and the locally approved product label.
