['Iron deficiency anaemia (IDA) that occurs in patients above the age of 45 years is often caused by gastrointestinal blood loss, and guidelines on the appropriate investigation of these patients have been published. There are few data regarding patients with iron deficiency who are not anaemic and it is not clear how these patients should be managed.', 'We set out to investigate the hypothesis that similar pathologies are likely to underlie iron deficiency and IDA, and to assess whether IDA was being investigated according to the guidelines published by the British Society of Gastroenterology (BSG).', 'The pathology computer identified 153 consecutive patients over the age of 45 years who had serum ferritin levels below 20 microg/dl (normal range 20-200 microg/dl) in a 2 month period (i.e., October and November 2000). Medical records were examined and we recorded all investigations, the diagnoses reached, and the investigating specialty. The results were compared using odds ratios (ORs) and 95% confidence intervals (CIs).', 'The study shows that the causes of iron deficiency and IDA are similar, but IDA is investigated more thoroughly than iron deficiency, OR 2.07 (CI 1.08-3.97). Ten patients with iron deficiency without anaemia were found to have coeliac disease, a significant result, OR 6.71 (CI 1.38-32.6). The majority of patients with IDA are not under the care of a gastroenterologist and this group are significantly less likely to be investigated according to the BSG guidelines, OR 0.15 (0.04-0.6).'] Do patients over 45 years with iron deficiency require investigation?