1 Asymptomatic autoimmune gastritis likely precedes gastric atrophy by 10 to 20 years, followed by the onset of iron-deficiency anemia that occurs as early as 20 years before vitamin B 12 deficiency pernicious anemia
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Content Enjoy sex like you used to Reviewed by Kelly Brown MD, MBA Written by Daniel Yetman Published 07/05/2025 Updated 06/30/2025 Vitamin B12 overdose is so rare that serious adverse effects from consuming large amounts of vitamin B12 have only been reported in a handful of studies in the medical literature
22,23 In patients with a normal or low-normal serum vitamin B 12 level, complete blood count results demonstrating macrocytosis, or suspected clinical manifestations, a serum methylmalonic acid level is an appropriate next step 1,2,6,18 and is a more direct measure of vitamin B 12 's physiologic activity