Investigating iron status in microcytic anaemia

Editor—The case of renal carcinoma presenting as mild microcytic anaemia described by Galloway and Smellie is not rare.¹ As well as a normal serum ferritin, such patients have a characteristic pattern of low serum iron and low serum transferrin, whereas iron deficient patients have low serum iron and high transferrin—provided the patient is not taking iron at the time of the test.

When anaemia of chronic disease is diagnosed, the hunt for a cause proceeds entirely differently from iron deficiency: chest x ray and abdominal ultrasonography rather than investigation of the gastrointestinal tract. Occult malignancy is high on the list. (Other causes such as rheumatoid are usually obvious.) Too many such patients linger on endoscopy and barium enema waiting lists. I highlight this important diagnosis in my first lecture to first year students.