Myeloperoxidase Stain
Also known as: MY PEROX
Use
The myeloperoxidase staining is helpful in differentiating myeloid leukemias. This test is used primarily to determine the myeloid lineage in acute myeloid leukemia (AML) per the WHO classification. It helps in recognizing certain subtypes of leukemia where myeloperoxidase positive granules are present in specific cells such as myeloblasts, promyelocytes, myelocytes, metamyelocytes, neutrophils, eosinophils, and monocytes. Monocytes stain diffusely and with less intensity compared to neutrophils and eosinophils. However, it is less sensitive and specific than flow cytometry immunophenotyping and its results must be interpreted within the clinical context. This test alone should not be used to establish a diagnosis.
Special Instructions
Transport requires 6 unfixed, air-dried, and unstained smears made from either whole blood or bone marrow aspirate, ensuring they are accompanied by 5 mL of whole blood. Samples must reach the lab within 48 hours of collection. Testing is performed from Monday to Friday.
Limitations
The test has limitations in terms of sensitivity and specificity compared to flow cytometry methods. It cannot be used as a standalone diagnostic tool for leukemia, particularly because the intensity of staining can vary among myeloid cells. The cytochemical nature of the stain may miss some acute myeloid subtypes with less conspicuous peroxidase activity, and it does not detect peroxidase deficiencies. Additionally, its utility may be impacted by improperly prepared or aged samples beyond the recommended time frames, particularly for smears and non-ambient conditions.
New York Approved
Methodology
Cell-based / Cytometry (Cytochemical Stain)
Biomarkers
LOINC Codes
- 32817-9
Result Turnaround Time
1-5 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
5 mL
Minimum Volume
Not provided
Container
Lavender (EDTA) or green (sodium or lithium heparin) or heparinized aspirate of bone marrow
Collection Instructions
Transport 6 unfixed, air-dried, and unstained push smears AND 5 mL whole blood (smears should be made from the blood submitted). OR 6 unfixed, air-dried, and unstained bone marrow aspirate smears.
Storage Instructions
Room temperature. Testing must be performed within 48 hours of collection.
Causes for Rejection
Frozen specimens. Peripheral blood smears older than one week. Anticoagulated blood or bone marrow sent without well-prepared unfixed smears if greater than 48 hours old.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | Unacceptable |
| Frozen | Unacceptable |