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Siderocyte Number Fraction, Bone Marrow — Prussian Blue Stain

Published: August 9, 2026Updated: August 16, 2026

A microscopic bone marrow test that uses a Prussian blue stain to identify and count iron-containing red blood cell precursors called siderocytes or sideroblasts.

Quick summary

["This test shows how much stainable iron is present in developing blood cells in the bone marrow."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
99397-2
Short code
Siderocytes.Tp 2 NFr Bld/Mar Prus Bl St
Synonyms
Siderocytes.Tp 2 NFr Bld/Mar Prus Bl St
Category
liver
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
prussian-blue-stain
CPT
86592
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

This test examines a bone marrow sample to identify and count siderocytes, also called sideroblasts, which are developing red blood cells that contain visible iron. A Prussian blue stain makes the iron easier to see under a microscope.

Why might I need this test?

A clinician may order this test when investigating unexplained anemia, iron overload, or a possible problem with how the body makes or uses iron. It is generally part of a broader evaluation that may also include blood counts and iron studies.

How is the test performed?

A bone marrow sample is collected and prepared on laboratory slides. The slides are treated with a Prussian blue stain and examined by a pathologist or other laboratory specialist, who reports the amount of iron-containing cells and the amount of visible iron.

How do I prepare for the test?

No fasting or special diet is usually required for the laboratory analysis itself. If a new bone marrow sample must be collected, follow the clinic's instructions about medications, local anesthetic, and possible sedation, and tell the clinician about bleeding disorders or blood-thinning medicines.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Bone marrow siderocyte count

Frequently asked questions

Are siderocytes the same as sideroblasts?
The terms are often used interchangeably. They refer to iron-containing precursors of red blood cells found in the bone marrow.
Is this the same as a routine blood iron test?
No. A routine blood iron test measures iron circulating in the blood, while this test uses a stained bone marrow sample to show iron stored in developing blood cells.
Does this test require a bone marrow biopsy?
The analysis requires a bone marrow sample, but the exact collection method depends on the procedure ordered by your clinician. The laboratory portion itself does not require a separate biopsy.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy