This iron deficiency calculator determines the iron deficit based on patient weight, hemoglobin and iron stores to prepare for iron replacement. There is in depth information below the form on the method used and on the result provided.
How does this iron deficiency calculator work?
This health tool computes the iron deficit based on patient parameters and the Ganzoni formula.
There are four fields that need to be completed:
■ Weight – body weight is used to establish iron deficit and is also taken into account when estimating the iron stores. The original formula employs the weight in kg but users can input it in lbs and it gets transformed.
■ Hemoglobin – there are two fields for hemoglobin input, one for the target and another for actual value. These can be input in g/dL, g/L or mmol/L. The normal ranges are: for males 13.8 to 18.0 g/dL (138 to 180 g/L, or 8.56 to 11.17 mmol/L) and for females 12.1 to 15.1 g/dL (121 to 151 g/L, or 7.51 to 9.37 mmol/L).
■ Iron stores – 500 mg for body weight greater than or equal to 35 kg (77 lbs) and 15 mg/kg for body weight less than 35 kg.
The Ganzoni equation used by the iron deficiency calculator is the following:
Total iron deficit (mg) = Weight in kg x (Target Hb - Actual Hb in g/dL) x 2.4 + Iron stores
The recommendation is that most adults need a cumulative dose of elemental iron of at least 1 g.
Iron replenishment can be done intravenously, either as total dose (example: iron-dextran or iron – carboxymaltose) or as split dose (example: iron sucrose).
The iron formulation choice remains for the clinician to make. It varies from increases in dietary intake of iron (usually for prophylaxis purposes) to oral, intramuscular or intravenous therapy.
Iron supplements, regardless of their way of administration, are used to replete body stores and to correct anemia.
Intravenous therapy is usually recommended in case of contraindications to oral iron, comorbidities that prevent absorption, chronic renal impairment or iron replacement needs to be rapid.
Iron deficiency anemia
Iron deficiency can occur at any stage of life, due to physiological demands, for example, during pregnancy, childhood growth or prolonged periods of sickness.
Iron metabolism needs to be balanced and bleeding, the major cause of iron deficiency (for instance in menstruation in females and chronic occult gastrointestinal bleeding) needs to be addressed.
Anemia caused by the depletion of iron is called iron deficiency anemia. IDA symptoms vary, may not be specific and include tiredness, weakness, shortness of breath. Fulminant symptoms include confusion, sensation of passing out, paleness.
IDA diagnosis is based on full blood examination and on the serum ferritin level.
The therapeutic management of IDA focuses on the replenishment of the iron stores through methods that have been mentioned above.
Example of a calculation
Taking the case of a patient weighing 75 kg (165.3 lbs) with a target hemoglobin value of 13 g/dL (130 g/L or 8.07 mmol/L), an actual hemoglobin of 9.5 g/dL (95 g/L or 5.9 mmol/L) and iron stores of 500 mg, the iron deficit is:
Iron deficit = 75 x (13 – 9.5) x 2.4 + 500 = 1,130 mg
Iron deficit / kg body weight = 15 mg.
Since this is less than the threshold of total dose of 20 mg/kg, the deficit can be eliminated with a single infusion.
References
1) Ganzoni AM. (1970) Intravenous iron-dextran: therapeutic and experimental possibilities. Schweiz Med Wochenschr; 100(7):301-3.
2) Koch TA, Myers J, Goodnough LT. (2015) Intravenous Iron Therapy in Patients with Iron Deficiency Anemia: Dosing Considerations. Anemia; 2015: 763576.
3) Bayraktar UD, Bayraktar S. (2010) Treatment of iron deficiency anemia associated with gastrointestinal tract diseases. World J Gastroenterol; 16(22): 2720–2725.
4)Pasricha SR, Flecknoe-Brown SC, Allen KJ, Gibson PR, McMahon LP, Olynyk JK, Roger SD, Savoia HF, Tampi R, Thomson AR, Wood EM, Robinson KL. (2010) Diagnosis and management of iron deficiency anaemia: a clinical update. Med J Aust; 193(9):525-32.
20 Aug, 2016