Management of Anemia in Dialysis Patient with Functional Iron Deficiency
This patient has functional iron deficiency (low TSAT with high ferritin) and should receive intravenous iron supplementation despite the elevated ferritin of 890 ng/mL, as the low TSAT of 23.5% indicates insufficient iron availability for erythropoiesis. 1, 2
Understanding the Iron Parameters
Your patient presents with a classic pattern of functional iron deficiency:
- Hemoglobin 110 g/L (at target per guidelines) 1
- TSAT 23.5% (calculated from iron 9.7 and TIBC 41.2) - below optimal target
- Ferritin 890 ng/mL - elevated but does not contraindicate iron therapy when TSAT is low
The low TSAT (<25%) with elevated ferritin indicates that stored iron is not being mobilized effectively for red blood cell production, a condition termed functional iron deficiency. 1, 3
Treatment Recommendation
Intravenous Iron Administration
Administer IV iron supplementation to increase TSAT above 25% and optimize erythropoiesis, even with ferritin >800 ng/mL. 1, 2
- The 2008 Canadian Society of Nephrology guidelines specifically address this scenario, recommending consideration of IV iron when ferritin is 800-1200 ng/mL if TSAT <25% and hemoglobin is suboptimal or ESA doses are high 1
- Give 100-125 mg IV iron at each hemodialysis session for 8-10 consecutive doses to address the functional deficiency 2, 4
- The American Journal of Kidney Diseases supports higher TSAT targets of 30-50% to optimize ESA response and reduce ESA requirements by up to 40% 2
Safety Monitoring
Withhold IV iron only if TSAT exceeds 50% or ferritin exceeds 800 ng/mL AND TSAT is adequate. 2, 4
- In this case, while ferritin is 890 ng/mL (slightly above 800), the low TSAT of 23.5% justifies continued iron therapy 1
- Monitor TSAT and ferritin every 3 months during maintenance therapy 2, 4
- Ferritin levels of 300-800 ng/mL are common in dialysis patients without evidence of adverse iron-mediated effects 2
ESA Management Considerations
Evaluate whether the patient is receiving erythropoiesis-stimulating agents (ESAs), as this influences iron requirements. 1, 5, 6
- If on ESAs: The functional iron deficiency is likely ESA-induced, as EPO stimulates erythropoiesis beyond the rate at which stored iron can be mobilized 1
- Administer supplemental iron when serum ferritin is less than 100 mcg/L or when serum transferrin saturation is less than 20% per FDA labeling for both epoetin alfa and darbepoetin alfa 5, 6
- If not on ESAs and hemoglobin remains at 110 g/L: Consider initiating ESA therapy only if hemoglobin drops below 100 g/L, as current hemoglobin is at guideline target 1, 5, 6
Maintenance Strategy After Initial Course
Once TSAT reaches >25%, transition to maintenance dosing of 25-125 mg IV iron weekly to prevent recurrent functional iron deficiency. 2, 4
- Hemodialysis patients require ongoing IV iron due to substantial blood losses from dialysis procedures, residual blood in tubing, frequent blood sampling, and poor oral absorption 2
- Need-based, continuous, low-dose iron (10-60 mg given 1-3 times weekly based on monthly TSAT and ferritin monitoring) achieves better hemoglobin response than intermittent pulse dosing 7
Common Pitfalls to Avoid
Do not withhold iron solely based on elevated ferritin when TSAT is low. 1
- The combination of high ferritin with low TSAT specifically indicates functional iron deficiency requiring treatment 1, 3
- Ferritin is an acute phase reactant and may be elevated due to inflammation rather than true iron overload 3, 8
- Serum ferritin remains the most reliable diagnostic parameter for iron stores in stable dialysis patients, but must be interpreted alongside TSAT 8
Oral iron is inadequate for hemodialysis patients and should not be used as primary therapy. 1, 2