Can a Vitamin B12 (Cobalamin) deficiency cause thrombocytopenia?

From the Research

Yes, vitamin B12 deficiency can cause thrombocytopenia, which is a condition characterized by low platelet counts, as evidenced by a recent case report published in 2023 1. This occurs because vitamin B12 is essential for DNA synthesis and cell division, particularly in rapidly dividing cells like those in the bone marrow. When B12 levels are inadequate, the bone marrow cannot effectively produce sufficient platelets, leading to thrombocytopenia. This hematologic manifestation often occurs alongside other cytopenias such as anemia and leukopenia, collectively known as pancytopenia. Some key points to consider in the diagnosis and treatment of vitamin B12 deficiency-induced thrombocytopenia include:

• The importance of considering vitamin B12 deficiency in the diagnostic workup of isolated thrombocytopenia, as highlighted in a 2023 case report 1
• The potential for vitamin B12 deficiency to mimic other hematological disorders, such as thrombotic thrombocytopenic purpura (TTP), as noted in studies from 2021 2, 3 and 2024 4, 5
• The effectiveness of vitamin B12 supplementation in resolving thrombocytopenia and other cytopenias associated with vitamin B12 deficiency, as demonstrated in the 2023 case report 1 and other studies 2, 3, 4, 5 Treatment involves vitamin B12 supplementation, typically starting with intramuscular injections of 1000 mcg daily or every other day for one week, followed by weekly injections for a month, and then monthly maintenance doses. Oral supplementation (1000-2000 mcg daily) may be used in some cases, though absorption issues often make injections more effective, especially in cases of pernicious anemia or malabsorption. Platelet counts typically begin to improve within days to weeks of starting B12 replacement therapy, with complete resolution of thrombocytopenia as B12 levels normalize. It is essential to prioritize the diagnosis and treatment of vitamin B12 deficiency to prevent severe hematologic complications and improve patient outcomes, as emphasized in the recent studies 1, 4, 5.