Review of vitamin B12 deficiency management in a family medicine clinic

Abstract

Objective: To review the current practice for patients diagnosed with vitamin B12 deficiency in a family medicine clinic. Design: Retrospective case notes review. Subjects: Patients attending the authors' family medicine clinic and prescribed with vitamin B12 supplement. Main outcome measures: Information collected included patient demographics, history of gastrectomy or significant gastric disease, diet history, auto-antibody levels, medications prescribed, vitamin B12 levels (pre-and post-), and reasons for checking B12 levels. Results: During the study period, 170 patients had been prescribed with any form of vitamin B12. In 47.6% of patients, testing was performed as screening among diabetics taking metformin. The mean baseline serum vitamin B12 level at diagnosis was 146.3pmol/L. Baseline levels were greater than 179pmol/L among 13% of patients. 73% and 27% were initially put on oral route and parenteral supplementation respectively. Among those on oral supplementation initially, 4% were changed to the parenteral route. Among those on parenteral supplementation initially, 35% were changed to the oral route. There was variation with regards to whether a loading regime was used or not among those receiving intramuscular injection. For those with a baseline level less than 200pmol/L, oral supplementation was comparable to injection with at least 90% cases attaining levels greater than 200pmol/L. Both routes achieved significant increases in B12 level (222.6 and 489 respectively). The commonest causes of B12 deficiency identified were metformin-related, followed by pernicious anaemia and diet related to insufficient meat intake. In 52% of patients, either one or both of anti-IF and anti-PA were checked. Subsequently 21 patients were diagnosed with pernicious anaemia. Among the 21 cases of pernicious anaemia, only 10 cases were more likely to have a true diagnosis of pernicious anaemia (anti-IF greater than 20 RU/ml). However, among these, three patients were prescribed with oral vitamin B12 and resulted in a significant mean B12 increase of 294 pmol/L. Conclusion: Vitamin B12 deficiency is not an uncommon condition seen in primary care setting. Pernicious anaemia may be under-diagnosed when there are other possible concomitant causes. Among those with pernicious anaemia, oral supplementation may be effective in restoring vitamin B12 level, although a minority of patients may still be under-treated due to suboptimal doses. Future studies will be needed to help setting up guidelines so that front-line doctors can manage patients in a more effective manner.