Differentiating Rifampicin-Induced Pancytopenia from Vitamin B12 Deficiency

Key Diagnostic Features

Low serum B12 levels are associated with B12 deficiency, which can cause pancytopenia, according to the American Heart Association 1, 2
B12 deficiency develops gradually over months to years as body stores are depleted, as stated by the American College of Physicians 2, 3

Elevated methylmalonic acid and homocysteine levels are indicative of B12 deficiency, even when serum B12 is in the normal range, as reported by the American College of Physicians 2, 3
Active B12 measurement is a more sensitive marker than total B12 for detecting B12 deficiency, according to the American College of Physicians 2, 3

B12 deficiency often presents with neurological symptoms, such as paresthesias, ataxia, and cognitive difficulties, as stated by the American Heart Association 1, 2
Glossitis and optic nerve dysfunction are also common presentations of B12 deficiency, as reported by the American College of Physicians 2

A diet low in vitamin B12, such as a vegan or vegetarian diet, is a risk factor for B12 deficiency, as stated by the American College of Physicians 2
Atrophic gastritis affecting the gastric body and autoimmune conditions, such as thyroid disease and type 1 diabetes, are also risk factors for B12 deficiency, according to the American College of Physicians 2, 3
Certain medications, including colchicine, H2 receptor antagonists, and metformin, can affect B12 absorption and increase the risk of deficiency, as reported by the American College of Physicians 2, 3