From the Guidelines
Ferritin levels after IV Cosmofer administration should be evaluated 4 to 8 weeks after the last infusion and are expected to increase, with a goal ferritin level of 50 ng/mL in the absence of inflammation.
Key Points
- The frequency of administration and duration of benefit of IV iron is dependent on the underlying etiology of iron deficiency (ID) 1.
- Laboratory evaluation following IV iron should include a complete blood count (CBC) and iron parameters, such as ferritin and percent transferrin saturation (TSAT), 4 to 8 weeks after the last infusion 1.
- Ferritin levels should not be evaluated within 4 weeks of a total dose infusion (TDI), as the circulating iron interferes with the assay leading to specious results 1.
- In the absence of inflammation, the goal ferritin is 50 ng/mL, regardless of sex at birth 1.
- The use of soluble transferrin receptor (sTfR) has been shown to be more sensitive in patients with inflammatory conditions where the ferritin (but not the TSAT) is unreliable for evaluation of ID and iron deficiency anemia (IDA) 1.
Expected Ferritin Levels
- The expected ferritin levels after IV Cosmofer administration can vary depending on the individual patient's response to treatment and the presence of underlying inflammatory conditions.
- A study published in the American Journal of Kidney Diseases recommended that enough IV iron should be given to increase the serum ferritin levels to 200 to 400 ng/mL and/or transferrin saturation values to between 25% and 35% before initiating Epoetin therapy 1.
- However, this recommendation may not be applicable to all patients, and the goal ferritin level of 50 ng/mL in the absence of inflammation is a more generally accepted target 1.
The FDA Drug Labels for iron (IV) do not address this question.
From the Research
Ferritin Levels after IV Cosmofer Administration
- Ferritin levels increased after IV Cosmofer administration, with a mean increase from 93.5 to 302.6 ng/ml at 6 weeks follow-up in patients with chronic kidney disease and iron deficiency anaemia 2
- In another study, serum ferritin levels rose sharply after intravenous iron dextran infusion, reaching peak levels 7-9 days after infusion 3
- The sensitivity and specificity of serum ferritin as a marker of iron status after intravenous iron dextran were assessed, with a sensitivity of 60% and specificity of 30% when used alone 4
- In a study comparing IV ferric carboxymaltose and iron(III) hydroxide dextran (Cosmofer) in pregnancy, ferritin levels were comparable in the two groups at baseline, but the study did not report on the change in ferritin levels after Cosmofer administration 5
Factors Affecting Ferritin Levels
- The dose of IV iron administered was poorly correlated to changes in serum ferritin levels 4
- Maintaining a serum ferritin level of 600-700 ng/mL by IV iron administration can decrease erythropoietin dose requirements in chronic hemodialysis patients with functional iron deficiency anaemia 6
Monitoring Ferritin Levels
- Serum ferritin and transferrin saturation are non-specific and insensitive indicators for accurate diagnosis of iron deficiency in hemodialysis patients on erythropoietin 4
- The predictive value of serum ferritin and transferrin saturation for monitoring IV iron therapy is limited, with a predictive value of 48% for transferrin saturation and 45% for serum ferritin when used alone 4