8th February 2024

A 34-year-old female with known Hashimoto’s thyroiditis presents with anaemia found on routine blood tests.

A 34-year-old female with known Hashimoto’s thyroiditis presents with anaemia found on routine blood tests. She has noted a three-year history of progressive tiredness, weight loss, shortness of breath and light-headedness. She has also experienced tingling around her fingertips over the past two months. 

This revealed a macrocytic anaemia with low B12 levels. Further blood tests revealed anti-intrinsic factor antibodies. 

Given the likely condition, which of the following cells produces the substance that has been affected?