Association between the Level of Serum Vitamin B12 and Venous Thromboembolism in African American Population
Authors: Khillan Ratesh , Yu Nyein Htway , Ouyang Haoxu , Preet Mohan 
Published: November 2019

Background
Multiple risk factors have been linked to venous thromboembolism (VTE). It is well established that elevated level of homocysteine correlated with increased risk of VTE. Some studies showed that vitamin B12 deficiency may be the cause for homocysteinemia. Therefore, it is recommended by some groups that vitamin B12 should be supplemented in the patient with high homocysteine to prevent VTE. However, more recent study has shown that there is correlation between the high serum Vitamin B12 level and risk of VTE in cancer patients.[1] provoked VTE after orthopedic surgery was also shown to be associated with elevated vitamin B12 serum levels in elderly patients. The role of vitamin B12 in VTE patients is not fully understood. Our study is to see whether there is correlation between serum Vitamin B12 level and risk of VTE in general population.
Methods
177 Patients admitted to Kingsbrook Jewish Medical Center between January 1st, 2015 to December 31st, 2018 with the diagnosis of VTE were identified. 95 cases had measured serum Vitamin B12 results within 3 months. 97 patients without any history of VTE who were seen in the hematology clinic during the same period time were used as control in this study. Demographic information and Vitamin B12 level were collected. T test and chi-square were used for statistical analysis.
Results
VTE patients had a median age of 70, which is significantly higher than the median age of 57 in the control group. The mean level of vitamin B12 in control group was 620 pg/mL, which was lower than the average vitamin B12 level (770 pg/mL, p=0.0344) in the VTE group. When we divided the patients into 3 groups based on Vitamin B12 level: Low B12 (<250 pg/mL), Moderate B12 (250-800 pg/mL) and High B12 (>800 pg/mL). We observed 41% of VTE patients have B12 level more than 800 pg/mL while only 20% of control patients have high B12 level (chi-square, p=0.006).
Discussion
Our study showed that vitamin B12 level is significantly elevated in patients diagnosed with VTE and more than 40% of those patients actually have vitamin b12 level more than 800 pg/mL. It is known that elevated vitamin B12 level is associated with inflammation and increased mortality.[2] An association between elevated B12 levels and cancer has been reported in several studies [3]. It is unclear elevated vitamin B12 levels predict undiagnosed cancer which is a known risk factor for VTE or vitamin B12 directly contribute hypercoagulation. Nevertheless, we should be cautious when supplementing vitamin B12 and the dosage may need to be titrated closely. More clinical studies are definitely warranted.
References
1. Arendt JFH, el al. Elevated plasma vitamin B12 levels and risk of venous thromboembolism among cancer patients: A population-based cohort study. PubMed ID: 26724465
2. Grossfeld A1, et al. Symptomatic venous thromboembolism in elderly patients following major orthopedic surgery of the lower limb is associated with elevated vitamin B12 serum levels. PubMed ID:23000313
3. Johan F.H. Arendt, Henrik T. Sørensen, Laura J. Horsfall and Irene Petersen. Elevated Vitamin B12 Levels and Cancer Risk in UK Primary Care: A THIN Database Cohort Study. EPI-17-1136 Published April 2019

Disclosures
No relevant conflicts of interest to declare.