Reticulocyte Hemoglobin Content (RET-He)
RET-He measures the hemoglobin packed into new red cells, revealing iron availability in real time — often before hemoglobin itself drops.
Updated: 8/26/2026
Reference ranges (typical adult values)
| Who | Range | Unit |
|---|---|---|
| Adults | 28 – 35 | pg |
Ranges differ between laboratories — the range printed on your own report always applies first.
What is Reticulocyte Hemoglobin Content (RET-He)?
RET-He measures the amount of hemoglobin packed into reticulocytes — immature red blood cells released from the bone marrow within the past 1–2 days. Because reticulocytes are so freshly made, RET-He reflects how much iron was available to the marrow at the moment of their production.
This makes RET-He fundamentally different from ferritin (long-term stores) or hemoglobin (average across all cells with 120-day lifespan). RET-He gives a real-time snapshot of iron sufficiency for erythropoiesis.
Reference Range
28 – 35 pg
Reference intervals may vary between laboratory platforms.
Why Might It Be Low?
A low RET-He means insufficient iron is reaching the marrow:
- Absolute iron deficiency — depleted iron stores. RET-He often falls before hemoglobin changes.
- Functional iron deficiency — stores may be normal but iron transport is impaired (chronic inflammation, chronic kidney disease).
- Iron-restricted erythropoiesis — inflammatory cytokines block iron mobilization.
- Recent dietary iron insufficiency.
Why Might It Be Elevated?
- Iron overload (hemochromatosis, excessive supplementation).
- Some hemolytic states with compensatory erythropoiesis.
- Thalassemia trait.
What to Do Next
RET-He is most informative alongside serum ferritin, transferrin saturation, hemoglobin, and MCV. Do not self-initiate iron supplementation based solely on a low RET-He.
Monitoring Over Time
RET-He begins to rise within 1–2 weeks of starting effective iron supplementation — well before hemoglobin or MCV improve. This allows early confirmation that treatment is working. In patients on erythropoiesis-stimulating agents, serial RET-He guides iron dosing.
Questions to Ask Your Doctor
1. Does my RET-He suggest functional or absolute iron deficiency? 2. Would additional tests (soluble transferrin receptor, CRP, full iron panel) help clarify my status? 3. If I start iron supplementation, how quickly should RET-He normalize? 4. How frequently should RET-He be re-measured during treatment? 5. Are there dietary changes that could improve my RET-He?