Anemia is one of the few things in kidney disease that treatment reliably makes you feel. The fatigue lifts. That is worth doing well.
Iron before erythropoietin, always
The instinct is to reach for an ESA. It is usually the wrong first step.
Iron deficiency is nearly universal in chronic kidney disease. Inflammation raises hepcidin, which locks iron inside storage cells where the bone marrow cannot reach it. The consequence is counterintuitive and clinically decisive: a normal ferritin does not exclude iron deficiency.
So we measure ferritin and transferrin saturation together, and we use thresholds specific to kidney disease rather than the ones used in the general population.
For many patients, correcting iron corrects the anemia. No ESA required.
Why intravenous
Oral iron is poorly absorbed in chronic kidney disease. Hepcidin blocks absorption at the gut wall, the same mechanism that traps iron in storage. Patients take it faithfully for months and their hemoglobin does not move.
Intravenous iron bypasses that entirely. Ferric carboxymaltose, iron sucrose, ferumoxytol, and iron dextran are all effective. Infusion reactions occur but are uncommon with modern preparations, and we monitor for them.
| Treatment | How it works |
|---|---|
| Iron (oral or IV) | Replaces the raw material for red cells — the usual first step |
| ESA injections | Stimulate the marrow when erythropoietin is low |
| HIF-PHI (oral) | A newer pill that boosts your body's own erythropoietin |
When an ESA is added
Epoetin alfa or darbepoetin alfa, and the target is deliberately modest: hemoglobin between 10 and 11.5 g/dL.
The reason is not caution for its own sake. Trials that targeted normal hemoglobin found more strokes, more thrombosis, and more deaths. Correcting the number all the way harmed people.
This is one of the clearer cases in medicine where treating to a normal laboratory value is worse than treating to an abnormal one. We do not push past the target because the patient still feels tired, and we explain why.
What is checked before every dose
Iron stores, because an ESA cannot build red cells without iron and giving one to an iron-deficient patient wastes the drug and the visit.
Blood pressure, which ESAs raise.
And a hard look at whether the anemia is actually from kidney disease. Anemia out of proportion to the eGFR, or anemia that does not respond to iron and an ESA, means something else is happening: gastrointestinal bleeding, B12 or folate deficiency, hemolysis, myeloma, hypothyroidism.
Transfusion
Avoided when possible in transplant candidates, because transfusion sensitizes the immune system, raises panel reactive antibody, and makes finding a compatible donor harder.
That consideration is easy to overlook and expensive to get wrong.
What this looks like in practice
Labs, then iron, then reassess. An ESA only if the anemia persists once iron is repleted. Monitoring every few weeks during titration, then at longer intervals.
Most of the benefit comes from doing the first step properly.