From the Guidelines
Yes, vitamin B12 deficiency can cause low platelet counts (thrombocytopenia). B12 is essential for proper DNA synthesis and cell division, including the production of platelets in the bone marrow. When B12 levels are insufficient, the bone marrow cannot effectively produce enough platelets, leading to thrombocytopenia. This deficiency often causes other blood abnormalities as well, including anemia and abnormal white blood cell counts, a condition known as pancytopenia.
Key Points to Consider
- The most recent and highest quality study, 1, recommends treating vitamin B12 deficiency immediately to prevent further complications.
- Treatment typically involves B12 supplementation, with initial doses of hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months lifelong, as recommended by 1.
- For severe deficiency or neurological involvement, more frequent injections may be necessary, and urgent specialist advice from a neurologist and haematologist should be sought, as suggested by 1 and 1.
- Patients with B12 deficiency should also be evaluated for the underlying cause, such as pernicious anemia, strict vegetarian diet, or gastrointestinal disorders that affect absorption.
- Most patients see improvement in platelet counts within weeks of starting B12 therapy, though complete recovery may take longer depending on the severity and duration of the deficiency.
Important Considerations
- Folic acid deficiency may also contribute to megaloblastic anemia, but treating vitamin B12 deficiency is essential to prevent masking of the underlying condition, as noted in 1.
- Regular monitoring of platelet counts and other blood parameters is necessary to assess the effectiveness of treatment and adjust the dosage as needed.
- A comprehensive approach to managing vitamin B12 deficiency includes addressing the underlying cause, providing adequate supplementation, and monitoring for potential complications, as emphasized by 1 and 1.
From the Research
Vitamin B12 Deficiency and Low Platelets
- Vitamin B12 deficiency can cause low platelets, as evidenced by several case reports and studies 2, 3, 4.
- Thrombocytopenia, a condition characterized by low platelet count, can be a rare cause of isolated thrombocytopenia in adults, and vitamin B12 deficiency should be considered in the diagnostic workup 2.
- Severe vitamin B12 deficiency can mimic thrombotic thrombocytopenic purpura (TTP), a condition characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ damage 3, 4.
- Vitamin B12 deficiency can lead to ineffective erythropoiesis, intramedullary hemolysis, and neurologic deficits, which can be similar to the features of TTP 4.
- Treatment of vitamin B12 deficiency with supplementation can improve platelet count and resolve thrombocytopenia 2, 3.
Diagnostic Considerations
- Screening for vitamin B12 deficiency may be warranted in patients with risk factors, such as gastric or small intestine resections, inflammatory bowel disease, or use of certain medications 5.
- Initial laboratory assessment should include a complete blood count and serum vitamin B12 level, and measurement of serum methylmalonic acid may be used to confirm deficiency in asymptomatic high-risk patients with low-normal levels of vitamin B12 5.
- Diagnostic biomarkers for vitamin B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid 6.
Management and Treatment
- Oral administration of high-dose vitamin B12 (1 to 2 mg daily) is as effective as intramuscular administration for correcting anemia and neurologic symptoms 5.
- Intramuscular therapy leads to more rapid improvement and should be considered in patients with severe deficiency or severe neurologic symptoms 5.
- Patients who have had bariatric surgery should receive 1 mg of oral vitamin B12 per day indefinitely 5.