Reticulocyte hemoglobin (Ret-He)
A measure of how much haemoglobin is packed into the newest red blood cells (reticulocytes). Because it reflects iron supply to red-cell production right now, a low value is one of the earliest signs of iron-deficient red-cell formation — often before the standard iron tests change.
What it measures
Reticulocytes are the youngest red blood cells, just released from the bone marrow. Reticulocyte haemoglobin (Ret-He, or CHr) measures the amount of haemoglobin inside these newest cells. Because reticulocytes only live in the blood for a day or two, this number is a real-time snapshot of how well red-cell production is being supplied with iron. If iron is in short supply for making haemoglobin, the newest cells are made with less of it, and Ret-He falls — often earlier than a fall in the mature red-cell indices (like the MCV) and, in some situations, before ferritin and other markers give a clear answer. This makes it a useful, early and functional indicator of whether red-cell production is iron-limited. It is used to detect iron-restricted red-cell formation, to help distinguish iron deficiency from other anaemias, to monitor the response to iron treatment (a rising Ret-He is an early sign it is working), and it is especially valued in situations where ferritin is unreliable, such as inflammation or kidney disease. It complements, rather than replaces, the standard iron studies.
What a high value can mean
- A normal or high Ret-He — red-cell production has adequate iron; iron-restricted formation is unlikely.
- Following iron treatment — a rise indicates the newest cells are now being made with enough iron.
What a low value can mean
- Iron-restricted red-cell production — the classic meaning; an early functional sign of iron deficiency.
- Iron-deficiency anaemia — often before mature-cell indices fall.
- Functional iron deficiency in chronic inflammation or kidney disease — where iron is present but not available to the marrow.
- Some thalassaemias — can also lower it, so it is read in context.
When to discuss with a doctor
Reticulocyte haemoglobin is a functional marker used within an anaemia or iron workup rather than acted on alone. Its strength is timing and reliability: a low value flags iron-restricted red-cell production early, and it stays useful when ferritin is distorted by inflammation or kidney disease. A rising value after starting iron is an early, encouraging sign of response, while a value that does not rise may prompt a rethink of the diagnosis or of whether the iron is being absorbed. It is interpreted alongside the full blood count, reticulocyte count and standard iron studies. Mediora.AI can show Ret-He alongside ferritin, transferrin saturation and the blood count so an early or functional iron problem stands out; the interpretation and any treatment belong with your doctor.