However, they're relatively rare
We extracted data on first author, PubMed identification number, publication year, country of origin of the participants, study design, cohort name/or data source, the country of origin, the date of recruitments, study primary question, the number of participants, the type of cancer, age, sex, the follow up time in longitudinal or treatment studies, plasma B12 concentrations or other B12 markers measured in patients/controls, the inclusion and exclusion criteria of the original studies, B12 analytical method, effect size (i.e., RR, OR, HR), what was considered as exposed/not exposed, reference categories, and key results
If your doctor orders them and they come back mildly elevated (1-2 times upper normal), this is expected and does not require stopping the medication
Follow-up monitoring Labs repeated at 6090 days
The short answer most clinicians give surprises people: most of them take both