A diagnosis of MF is made based on the World Health Organization (WHO) criteria. There is no one test that can diagnose a person as having MF; the diagnosis is based on findings from a bone marrow biopsy exam, blood cell counts and chemistry, and physical exam.
In people who have no symptoms, MF may be suspected when a routine medical checkup reveals an enlarged spleen and abnormal blood test results.
The results of a blood test (a complete blood count, or CBC) that suggest a diagnosis of MF often include
- A decrease below the normal range in the number of red blood cells (anemia)
- An increase in the normal range in the number of white blood cells
- An increase above the normal range in platelet counts (for about one-third of patients)
- A mild to moderate decrease below the normal range in platelet counts (for about one-third of patients).
In addition to blood cell counts, blood tests may also show
- Teardrop-shaped red cells and immature red cells and white cells in the blood (seen by microscopic examination of the blood cells)
- Giant platelets, abnormal platelet formation and circulating dwarf megakaryocytes (bone marrow cells responsible for the production of platelets)
- Elevated serum levels of uric acid, lactic dehydrogenase (LDH), alkaline phosphatase and bilirubin
- Decreased serum levels of albumin, total cholesterol and high-density lipoprotein (HDL).
Bone Marrow Tests
Your doctor tests your bone marrow to help confirm a diagnosis. Bone marrow testing involves two steps usually performed at the same time in a doctor's office or a hospital:
- A bone marrow aspiration to remove a liquid marrow sample
- A bone marrow biopsy to remove a small amount of bone filled with marrow
Studying genetic components of the bone marrow cells can show mutations in the cells that may help eliminate other types of bone marrow disorders.
Your blood or bone marrow sample may be used for a lab test called a karyotype. In this test, a microscope is used to examine the size, shape and number of chromosomes in a sampling of cells. The results of the karyotype may be helpful in making certain treatment decisions.
A sample of blood or bone marrow may be analyzed in a laboratory to look for gene mutations, such as the JAK2, CALR, or MPL mutations, present in 90 percent of MF patients.
Ultrasound tests may be used to determine the size of the spleen. Magnetic resonance imaging (MRI) tests may be used to identify changes in the bone marrow that indicate MF.