Iron-studies
How do you diagnose IDA?
- IDA is diagnosed by haemoglobin less than the normal limit for the lab, MCV <76fl and ferritin <15ug/dl. Both microcytosis and hypochromia (MCH) are sensitive indicators of IDA. However they are also present in thalassaemia, sideroblastic anaemia, lead poisoning and anaemia of chronic disease.
- Ferritin is an acute phase reactant may be elevated, if concurrent inflammation is present. In such cases iron deficiency can be diagnosed by low serum iron and high TIBC or low transferrin saturation. In contrast anaemia of chronic disease has low serum iron and low TIBC with normal transferrin saturation.
- A bone marrow aspirate stained for iron (Perls stain) is diagnostic of iron deficiency. While this largely has been displaced in the diagnosis of iron deficiency by performance of serum iron, TIBC, and serum ferritin, the absence of stainable iron in a bone marrow aspirate is the criterion standard for the diagnosis of iron deficiency. It is diagnostic in identifying the sideroblastic anaemia’s by showing ringed sideroblasts in the aspirate stained with Perls stain.
Discuss iron replacement treatment?
- Oral replacement- This is achieved most simply and cheaply with ferrous sulphate 200 mg twice daily although ferrous gluconate and ferrous fumarate are as effective and may be better tolerated. A liquid preparation may be tolerated when tablets are not. Ascorbic acid enhances iron absorption and should be considered when response is poor.
- Parenteral replacement- should be used when there is intolerance to oral preparations or non-compliance.
- Parenteral preparations:
- Intravenous iron sucrose is well tolerated Bolus IV iron sucrose (200mg iron) over 10minutes is licensed and more convenient than a two hour infusion.
- IV iron dextran can replenish iron and Hb levels in a single infusion, but serious reactions can occur (0.6-0.7%) and there have been fatalities associated with infusion. However, it can be given via IM route when venous access is problematic.
- Sodium ferric gluconate
- IV iron sucrose and sodium ferric gluconate are rarely associated with severe allergic reactions and deaths, and are better tolerated than iron dextran even at high doses and thus are preferred.
Discuss the calculation of the parenteral iron dose?
Dose in mg of iron= body weight in kg X (12-present Hb. X10) X 0.24
Add to this a depot of 500mg.
Link to calculate parenteral iron dose
IV iron sucrose can be administered at 200mg weekly for five weeks. Alternatively, iron sucrose can be given at 500mg IV (in 250cc of NS) over four hours once weekly for two weeks.
