In this case scenario, we discuss the “double trouble” of using PPIs and metformin and their effects on vitamin B12.
Mrs. J is a 68-year-old woman with type 2 diabetes and gastroesophageal reflux disease (GERD). She has been taking metformin 1,000 mg twice daily for the past six years and omeprazole 20 mg daily for the past four years. She presents to her primary care provider with complaints of increasing fatigue, occasional dizziness, numbness and tingling in her hands and feet, and difficulty walking up stairs. She also reports mild forgetfulness over the past few months.
On physical examination, she appears pale, has mild distal paresthesias in both lower extremities, and a slightly unsteady gait. Vital signs are within normal limits, but laboratory studies reveal a hemoglobin of 10.8 g/dL, mean corpuscular volume (MCV) of 108 fL (macrocytic), and low serum vitamin B12 at 160 pg/mL. Folate levels are normal.
The primary care provider recognizes the patient is at risk for B12 deficiency due to her long-term use of both metformin, which can impair B12 absorption in the ileum, and omeprazole, which reduces stomach acid necessary for B12 release from dietary proteins (excellent board exam nugget).
She is started on oral vitamin B12 supplementation at 1,000 mcg daily, and her medications are reviewed. The provider discusses the risks and benefits of continuing long-term PPI therapy, emphasizing lifestyle modifications for GERD and considering step-down therapy if appropriate. The patient is educated on monitoring for neurological symptoms, adherence to supplementation, and the importance of follow-up labs to ensure her B12 levels normalize.
Over the next several months, Mrs. J’s fatigue improves, her gait steadies, and her neuropathic symptoms gradually lessen. Follow-up labs show normalization of her B12 levels, highlighting the importance of recognizing medication-related nutrient deficiencies in patients on long-term therapy.
If you are looking for more information on omeprazole, vitamin B12, and metformin, be sure to check out these podcast episodes:
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