Is it normal to have metamyelocytes present on a blood test result? Basically, does it adhere to the standard morphology of the WBC & platelet or is it indicative of something abnormal?
Cells of the blood are produced in the bone marrow by multiple steps of differentiation, yielding intermediate precursor cells like metamyelocytes.
Their presence in peripheral blood is abnormal. This is called myelocytosis or myelemia.
Myelocytosis is very concerning if there is presence of morphologically abnormal cells (like blast), especially if other lineages are lowered.
However, an isolated report of up to 2% circulating metamyelocytes is not as concerning. As they are the last step before the normal circulating neutrophils, the presence of metamyelocyte in the blood is indicative of high activity in the granulocytic lineage caused by :
- Compensating for a previously diminished number of neutrophils (for example, after chemotherapy)
- Active infection or inflammation, with elevated neutrophils (>7 giga/L)
- Use of granulocyte stimulating factor (G-CSF, filgrastim) for stem cell donation or recovery from agranulocytosis
If this finding persists across multiple blood draw, more severe causes may need to be considered :