Table 1. Causes of iron deficiency .

Cause	Example
Physiological
increased demand	Infancy, rapid growth, pregnancy, menstrual blood loss
Environmental	Insufficient intake e.g. vegan diet
Pathological
decreased absorption	Gastrectomy, duodenal bypass, Crohn’s disease
chronic blood loss	Gastrointestinal tract – peptic ulcer disease, colorectal cancer, angiodysplasia Systemic bleeding – postoperative, recent trauma
Drug related	Non-steroidal anti-inflammatory drugs, proton pump inhibitors, glucocorticoids
Genetic	Iron-refractory iron deficiency anaemia