From the Guidelines
INFeD infusion is typically reflected in blood work 4 to 8 weeks after the last infusion, as iron parameters should not be evaluated within 4 weeks of a TDI due to interference with the assay. According to the expert consensus guidelines 1, laboratory evaluation following IV iron should include a CBC and iron parameters (ferritin, percent transferrin saturation (TSAT)) 4 to 8 weeks after the last infusion. Hemoglobin concentrations should increase within 1–2 weeks of treatment and should increase by 1 to 2 g/dL within 4–8 weeks of therapy 1.
Some key points to consider when evaluating the response to INFeD infusion include:
- Hemoglobin levels usually start rising within 1–2 weeks of treatment 1
- Iron parameters, such as ferritin and TSAT, should not be evaluated within 4 weeks of a TDI, as the circulating iron interferes with the assay leading to specious results 1
- The full effect on hemoglobin may take 4-8 weeks to reach maximum improvement 1
- Reticulocyte Hb content, which can be measured by reticulocyte hemoglobin content (CHr) or reticulocyte hemoglobin equivalent (RET-He), is a direct assessment of the functional availability of iron to the erythropoietic tissue and can be used to detect ID and the need for iron replacement 1
It's essential to note that the frequency with which lab monitoring is required post-IV iron infusion is dependent on the cause of the ID, and those with recurrent blood loss will require more frequent and aggressive laboratory monitoring 1.
From the FDA Drug Label
Following intravenous administration, Venofer is dissociated into iron and sucrose and the iron is transported as a complex with transferrin to target cells including erythroid precursor cells. In 22 patients undergoing hemodialysis and receiving erythropoietin (recombinant human erythropoietin) therapy treated with iron sucrose containing 100 mg of iron, three times weekly for three weeks, significant increases in serum iron and serum ferritin and significant decreases in total iron binding capacity occurred four weeks from the initiation of iron sucrose treatment.
The effects of iron infusion are reflected in blood work four weeks after the initiation of treatment, as evidenced by significant increases in serum iron and serum ferritin, and significant decreases in total iron binding capacity 2.
- Key findings:
- Significant increases in serum iron and serum ferritin
- Significant decreases in total iron binding capacity
- Effects observed four weeks after initiation of treatment
- Main idea: The effects of iron infusion on blood work are reflected four weeks after the start of treatment.
From the Research
Timeframe for Infusion Reflection in Blood Work
- The timeframe for intravenous iron infusion to be reflected in blood work is not explicitly stated in the provided studies.
- However, study 3 mentions that the median change in hemoglobin, hematocrit, and ferritin was evaluated 8 to 12 weeks from baseline, suggesting that changes in blood work may be observable within this timeframe.
- Study 4 states that iron preparations can correct total iron deficit with single or repeated doses in 1-2 weeks, depending on the specific formulation, but does not provide a specific timeframe for when these changes would be reflected in blood work.
- Studies 5, 6, and 7 do not provide information on the timeframe for infusion reflection in blood work.