Reticulocytes %

The share of your red blood cells that are newly made, given as a percentage.

Last reviewedAugust 17, 2026

Whole blood

sample type

~3 mL

blood needed

~10 days

results in app

Any time of day

best timing

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On this page

Why test Reference ranges What you'll learn What affects it How testing works Sources FAQ

In short

Reticulocytes are red blood cells that have just been released from the bone marrow and have not fully matured. The percentage tells you how many of every hundred red blood cells in your sample are this young.

Because these cells mature within a day or two, the percentage reflects what your bone marrow has been doing in the last few days rather than over months.

Blood Health (CBC & Iron)

Reviewed against DGKL reference practice.

Why test this?

The percentage is the quickest way to see whether red blood cell production is stepped up or flat. It is the number most laboratories report first, and it moves within days of a change, which makes it useful for checking that a treatment is working.

It has one catch. Because it is a share rather than a count, it can look high simply because the total number of red blood cells is low. That is why it is read next to the absolute count.

What is a normal result?

Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.

Adult reference values as used by Aniva. Ranges are guidance and can vary by laboratory and method.

Group	Typical adult range
Adults	0.5 to 2.5 %

Confirm the exact interval with the reporting laboratory. Your Aniva report reads your result against these values together with your age, sex and the rest of your panel.

Ranges are guidance and vary by lab and assay, aligned with DGKL practice. Always read your result against your own lab's reference interval.

What insights will this test give you?

A fast read on whether your bone marrow is stepping up red blood cell production.
Early confirmation that iron, vitamin B12 or folate treatment is taking effect.
Context that separates a marrow that cannot keep up from one that is working hard against blood loss.

What can affect this result?

What can skew the result

The percentage can read high when the total red blood cell count is low, even if production has not truly increased. That is why the absolute count matters. Recent transfusion, bleeding and newly started supplements also shift it, and intervals differ between analysers.

Best interpreted with

Always read next to the absolute reticulocyte count, and together with haemoglobin, haematocrit and MCV.

How is this tested?

Sample

Whole blood

Blood needed

~3 mL

Method

Flow cytometry

Best timing

Any time of day

Sources. The evidence behind this

LOINC 17849-1: Reticulocytes per 100 erythrocytes in blood

MedlinePlus: Reticulocyte Count

Common questions

What does the reticulocyte percentage mean? It is the share of your red blood cells that are newly made. Higher means production is stepped up, lower means it is not.

Why is it read with the absolute count? A percentage can look high just because the total red cell count is low. The absolute count settles that.

Do I need to fast for this test? No. Eat and drink normally.

What can affect my result? Bleeding, transfusion, altitude, pregnancy, and recently starting iron, vitamin B12 or folate.

How long do results take? Results are usually ready in about 10 days.

What should I discuss with my clinician? Ask how this sits next to your haemoglobin and iron studies, and whether a repeat test after treatment makes sense.

Which Aniva panels include this marker?

Core

Your annual full-body baseline with more than 100 biomarkers, included in your Aniva membership.