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Understanding Bone Marrow Disorders: How Conditions Like Polycythemia Vera Begin

Feb 9, 2026

Key takeaways

  • Bone marrow disorders occur when the blood-forming marrow makes too many, too few, or abnormal blood cells. [1]
  • Polycythemia vera (PV) is a classic example of a disorder in which the marrow becomes overactive—most often linked to JAK2 mutations—and produces excess red blood cells (often with other lineages increased as well). [2][3]
  • Some bone marrow disorders may have limited symptoms early and can be detected through abnormal blood counts, prompting further evaluation (including bone marrow testing when indicated). In conditions such as polycythemia vera, timely management—such as maintaining hematocrit below 45%—is associated with a lower risk of major thrombotic/cardiovascular events. [1][4][5][6]

Overview

Bone marrow is the soft, spongy tissue inside certain bones where the body produces red blood cells, white blood cells, and platelets. When marrow output becomes abnormal—too high, too low, or dysregulated—bone marrow disorders can result and show up as abnormal blood counts on routine testing. [1]


These conditions range from mild to life-threatening and can be inherited or acquired. [1][7]

What are bone marrow disorders?

Bone marrow disorders are conditions where the marrow cannot produce healthy blood cells in the usual balance. Depending on which cell type is affected, people may develop: [1]


  • Anemia (too few red blood cells)
  • Infection risk (too few or dysfunctional white blood cells),
  • Bleeding/bruising (too few platelets), or
  • Problems related to overproduction of blood cells.


A practical way to classify many marrow disorders is by whether the marrow is underproducing or overproducing blood cells:

  • Bone marrow failure syndromes – where the marrow produces too few blood cells. [7]
  • Myeloproliferative neoplasms (MPNs)– where the marrow overproduces one or more blood cell types, including polycythemia vera. [2][8]

Polycythemia vera: A key bone marrow disorder

Polycythemia vera (PV) is classified as a myeloproliferative neoplasm. [8] It is commonly associated with a JAK2 mutation that drives neoplastic proliferation of hematopoietic progenitor cells, leading to increased red blood cell production and, in many patients, elevated white blood cells and/or platelets as well. [2]


PV complications are linked to increased blood viscosity and thrombotic risk, which is why ongoing clinical monitoring and management are important. [2] Over time, a minority of PV cases progress to post-PV myelofibrosis, and a smaller proportion transform to acute myeloid leukemia; reported estimates vary by cohort and follow-up duration. [11]

How is bone marrow examined?

When blood counts appear abnormal, clinicians may order bone marrow tests to evaluate how well the marrow is making blood cells and to look for patterns of disease. [1] These tests usually involve bone marrow aspiration (removing a small amount of fluid marrow) and bone marrow biopsy (removing a small piece of bone with marrow), often performed together and commonly sampled from the back of the hip bone. [1][12]


Bone marrow tests are used to help determine the cause of too many or too few blood cells (or abnormal-looking cells) and can support diagnosis and monitoring of many blood and marrow disorders, including polycythemia vera. [1]

Final thoughts

Bone marrow disorders underlie many hematologic diseases, including marrow failure syndromes and MPNs such as polycythemia vera. [1][8]


Understanding the marrow’s role helps you interpret abnormal blood tests, understand why a biopsy may be recommended, and plan longer-term care with a hematology team. [1][13]

Frequently asked questions (FAQs)

1. What is the main function of bone marrow?

Bone marrow makes red blood cells, white blood cells, and platelets. [1]


2. Are bone marrow disorders always cancerous?

Not always, Some marrow disorders are noncancerous, while others are neoplastic. PV is classified as a myeloproliferative neoplasm. [2][8]


3. How is polycythemia vera linked to bone marrow disorders?

PV is classified as a myeloproliferative bone marrow disorder, meaning the marrow makes too many blood cells, especially red ones, due to genetic mutations. [2]


4. What are inherited bone marrow failure syndromes?

These are rare genetic conditions—such as Fanconi anemia or Dyskeratosis congenita—where the marrow fails to make enough blood cells, often starting in childhood. [7]


5. How do doctors test bone marrow disorders?

Bone marrow testing typically includes aspiration and biopsy, often from the hip, to examine marrow and bone under the microscope and run additional tests. [1][2][13]

Abbreviation

  • PV — Polycythemia vera
  • MPNs — Myeloproliferative neoplasms
  • JAK2 — Janus kinase 2
  • post-PV — post–polycythemia vera
  • FAQs — Frequently asked questions


References

  1. National Library of Medicine. (2025, March 5). Bone marrow tests. MedlinePlus. https://medlineplus.gov/lab-tests/bone-marrow-tests/
  2. Lu, X., & Chang, R. (2023, April 24). Polycythemia vera. In StatPearls Publishing, StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK557660/
  3. Arber, D. A., Orazi, A., Hasserjian, R. P., Borowitz, M. J., Calvo, K. R., Kvasnicka, H.-M., & Wang, S. A. (2022). International Consensus Classification of myeloid neoplasms and acute leukemias: Integrating morphologic, clinical, and genomic data. Blood, 140(26), 2900–2913. https://doi.org/10.1182/blood.2022015850
  4. National Cancer Institute. (2024, October 4). Myelodysplastic syndromes treatment (PDQ®)–Patient version. https://www.cancer.gov/types/myeloproliferative/patient/myelodysplastic-treatment-pdq
  5. Benevolo, G., Vassallo, F., Urbino, I., & Giai, V. (2021). Polycythemia vera (PV): Update on emerging treatment options. Current Hematologic Malignancy Reports, 16(2), 185–195. https://doi.org/10.1007/s11899-021-00625-z
  6. Marchioli, R., Finazzi, G., Specchia, G., Cacciola, R., Cavazzina, R., Cilloni, D., De Stefano, V., Elli, E., Iurlo, A., Latagliata, R., Lunghi, F., Lunghi, M., Marfisi, R. M., Musto, P., Masciulli, A., Musolino, C., Cascavilla, N., Quarta, G., Randi, M. L., … Barbui, T. (2013). Cardiovascular events and intensity of treatment in polycythemia vera. The New England Journal of Medicine, 368(1), 22–33.
  7. Dokal, I., & Vulliamy, T. (2010). Inherited bone marrow failure syndromes. Haematologica, 95(8), 1236–1240. https://doi.org/10.3324/haematol.2010.025619 IF: 7.9 Q1 B1
  8. Barbui, T., Thiele, J., Gisslinger, H., Kvasnicka, H. M., Vannucchi, A. M., Guglielmelli, P., Orazi, A., & Tefferi, A. (2018). The 2016 WHO classification and diagnostic criteria for myeloproliferative neoplasms: Document summary and in-depth discussion. Blood Cancer Journal, 8(2), 15. https://doi.org/10.1038/s41408-018-0054-y IF: 11.6 Q1 B1
  9. Schoettler, M. L., & Nathan, D. G. (2018). The pathophysiology of acquired aplastic anemia: Current concepts revisited. Hematology/Oncology Clinics of North America, 32(4), 581–594. https://doi.org/10.1016/j.hoc.2018.03.001 IF: 2.7 Q2 B3
  10. Tashkandi, H., & Younes, I. E. (2024). Advances in molecular understanding of polycythemia vera, essential thrombocythemia, and primary myelofibrosis: Towards precision medicine. Cancers, 16(9), 1679. https://doi.org/10.3390/cancers16091679 IF: 4.4 Q2 B3
  11. Bose, P., Shallis, R. M., & Verstovsek, S. (2025). Polycythemia vera: Current management and future directions. Annals of Hematology, 104(10), 2711–2716. https://doi.org/10.1007/s00277-025-06001-3
  12. National Cancer Institute. (n.d.). Bone marrow aspiration and biopsy. NCI Dictionary of Cancer Terms. Retrieved February 2, 2026, from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/bone-marrow-aspiration-and-biopsy
  13. National Library of Medicine. (2024, June 17). Bone marrow biopsy. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/article/003934.htm