How to Use the Iron Deficiency Calculator
This iron deficiency calculator uses the Ganzoni equation to determine the total amount of iron that must be administered parenterally (as iron infusions) to a patient with iron deficiency anemia.
- Enter body weight — choose kg (metric) or lbs (American). If the patient is overweight, use their ideal body weight; if underweight (BMI < 18.5), use actual body weight.
- Select hemoglobin unit — g/dL (USA), g/L (Europe, Canada), or mmol/L.
- Enter actual hemoglobin — the patient's current measured hemoglobin level.
- Enter target hemoglobin — the desired hemoglobin level after treatment. Normal ranges: 12–15.5 g/dL for women, 13.5–17.5 g/dL for men.
The calculator will apply the Ganzoni formula and show the total iron deficit in mg along with the recommended number of infusion sessions.
What is Iron Deficiency Anemia?
Anemia (from Greek: "lack of blood") is medically defined as diminished levels of hemoglobin, hematocrit, and red blood cell count. Iron deficiency anemia means decreased or insufficient production of red blood cells due to low iron stores.
It is the most common nutritional disorder globally — in the USA, it affects approximately 2% of men and 10–20% of women. Iron deficiency is responsible for 25% of all anemia cases.
Common causes include:
- Insufficient dietary iron intake (especially during pregnancy or puberty)
- Heavy menstruation or abnormal postmenopausal bleeding
- Gastrointestinal bleeding (gastric ulcers, colorectal cancer)
- Impaired absorption (after gastrectomy or bariatric surgery)
Anemia Symptoms
Symptoms arise from insufficient oxygen supply to tissues and include:
- Shortness of breath
- Weakness and fatigue
- Rapid heart rate (tachycardia, >100 bpm)
- Headaches and dizziness
- Chest pains
- Paleness
- Brittle, thin hair and nails
- Cold hands and feet
- Soreness of the tongue (cheilosis)
If you experience these symptoms, consult your physician for a proper diagnosis.
Iron Deficiency Anemia Treatment
The first step is identifying the underlying cause. Treatment options include:
Oral Supplements
For moderate deficits, oral iron is the standard approach, continued for at least 3 months after the deficit is corrected. Side effects may include nausea and constipation.
Iron Infusion
Parenteral iron is used when:
- The deficit must be replenished quickly
- The patient cannot tolerate oral supplements
- Oral absorption is impaired (post-gastrectomy, bariatric surgery, inflammatory bowel disease)
Infusions are typically given 2–3 times per week, with a standard dose of 100–200 mg per session.
The Ganzoni Equation
The Ganzoni equation calculates the total iron deficit for parenteral supplementation:
Iron deficit [mg] = Body weight [kg] × (Target Hb [g/dL] − Actual Hb [g/dL]) × 2.4 + Iron stores [mg]
Where:
- 2.4 = 0.0034 × 0.07 × 1000 (iron content of hemoglobin 0.34% × blood volume ~7% of body weight × unit conversion)
- Iron stores = 500 mg for patients ≥ 35 kg; 15 mg/kg × body weight for patients < 35 kg
The result is the cumulative iron dose needed to replete iron stores. Divide by the dose per session (typically 200 mg) to get the number of infusions required.
Iron-Rich Foods
Supporting anemia treatment with dietary iron can help. Iron from animal sources (heme iron) is absorbed more efficiently than plant-based iron (non-heme iron). Consuming vitamin C with iron-rich meals significantly improves non-heme iron absorption.