AKT-2938

A 75-year-old woman is experiencing fatigue and shortness of breath. She appears to be anaemic and the following blood test results are significant:
Investigation Result Normal Value
Haemoglobin 68 g/l 115-155 g/l
White cell count 2.6 x 109/l 4.0-11.0 x 109/l
Platelets 160 x 109/l 150-400 x 109/l
Reticulocyte count 0.75% 0.5%-1.5%
Mean corpuscular volume 135 fl 76-98 fl
Ferritin 110 μg/l 10-120 μg/l
What is the most probable cause of her anaemia?