0
Editor's Correspondence |

The Long and Short of Metformin-Related Vitamin B12 Deficiency

George I. Varughese, MRCPI, MRCP(UK); Abd A. Tahrani, MD, MRCP; John H. B. Scarpello, MD, FRCP
Arch Intern Med. 2007;167(7):729-730. doi:10.1001/archinte.167.7.729-b.
Text Size: A A A
Published online

Extract

We applaud Ting et al1 for their study demonstrating the risk of vitamin B12 deficiency with increasing dose and duration of metformin use. In contrast to previous reports, their study demonstrated no excess risk of vitamin B12 deficiency among metformin users who currently use histamine2-receptor blockers or proton pump inhibitors.1 This statement should be interpreted very cautiously, although the authors allude to the fact that the lack of association in their study may stem from imprecise hospital-based medication records and inability to track the use of histamine2-receptor blockers or proton pump inhibitors. Gastrointestinal symptoms can be a limiting factor in optimizing metformin therapy, and metformin has been recognized not to alter intestinal motility or bacterial overgrowth.1,2 Interestingly, almost one half of adult consumers of over-the-counter histamine2-receptor blockers have been reportedly using these drugs in a manner inconsistent with Food and Drug Administration labeling, and this off-label use was associated with substitution for physician care.3 This has indeed clearly demonstrated that the over-the-counter use of such drugs are rampant, hence contributing to the reasons for the spectacular and rapid decline in antireflux surgery.4 Histamine2-receptor blockers or proton pump inhibitors impair the absorption of protein-bound dietary vitamin B12 and contribute to the development of B12 deficiency with prolonged use.5 The inhibition of acid secretion by the gastric parietal cells results in decreased gastric acid and pepsin secretion required for the cleavage of dietary B12.5 As an illustrative example, some of the reports cited from the literature do not even take into account the plausible role of histamine2-receptor blockers or proton pump inhibitors, and to our knowledge, a therapeutic trial of metformin therapy has never been attempted to identify whether metformin was genuinely the cause of vitamin B12 deficiency.5 This has particular inference, especially when the study by Ting et al1 has not been able to identify the exact mechanism of metformin-related vitamin B12 deficiency but only supports the notion of a causal relationship.5

Sign In to Access Full Content

Don't have Access?

Register and get free email Table of Contents alerts, saved searches, PowerPoint downloads, CME quizzes, and more

Subscribe for full-text access to content from 1998 forward and a host of useful features

Activate your current subscription (AMA members and current subscribers)

Purchase Online Access to this article for 24 hours

First Page Preview

View Large
/>
First page PDF preview

Figures

Tables

References

Correspondence

CME
Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Submit a Comment

Multimedia

Some tools below are only available to our subscribers or users with an online account.

Sign In to Access Full Content

Related Content

Customize your page view by dragging & repositioning the boxes below.

Articles Related By Topic
Related Topics
PubMed Articles
Jobs
brightcove.createExperiences();