A patient with anemia is found to have a low level of vitamin B12 and a high level of methylmalonic acid in their blood. What is the most likely cause of their anemia?

A Pernicious anemia ✓
B Iron deficiency anemia
C Folate deficiency anemia
D Sickle cell anemia

Explanation

Vitamin B12 plays a crucial role in the metabolism of fatty acids and amino acids. A deficiency in vitamin B12 can lead to an accumulation of methylmalonic acid, which is a hallmark of pernicious anemia.

Mnemonic

Pernicious = permanent damage to stomach lining

Source

Harrison's Principles of Internal Medicine
Hematology Hematology: Anemia Hematology: Anemia Hard MEDICAL Confidence: high