Silent angiodysplasia and occult haemobilia as rare but treatable causes of refractory iron deficiency--two case reports.

Once menorrhagia has been excluded in females then, in both sexes, the gastrointestinal tract remains the commonest site for haemorrhage. This may be of surprisingly large volume but intermittent and therefore not universally demonstrated on stool testing. However, if loss is persistent it may nevertheless culminate in absolute iron deficiency and thus, even when occult blood is not present on repeated examinations, quantitation using chromium labelled red cells becomes invaluable.