Soluble transferrin receptor as a diagnostic laboratory test for detection of iron deficiency anemia in acute illness of hospitalized patients

Background: Many patients in the internal medicine ward have anemia. The etiology for the anemia may be multifactorial and, in the setting of inflammatory process when the ferritin is increased, it is difficult to diagnose iron deficiency anemia. Soluble transferrin receptor (sTfR) had been suggested as an indicator for iron deficiency. No study has investigated the meaning of high sTfR as the only positive marker of iron deficiency anemia (IDA) caused by gastrointestinal tract (GIT) bleeding in hospitalized patients. Objectives: To demonstrate the importance of high levels of sTfR as a marker for further GIT investigation in cases of anemia where the level of ferritin was normal or increased. Methods: We retrospectively assessed all patients in an internal medicine ward in our facility who had anemia, high sTfR levels (> 5.0 mg/L) and normal or high ferritin levels and who underwent esophagogastroduodenoscopy and colonoscopy. Results: Of 32 patients with anemia and normal or high ferritin levels and high sTfR, 22 patients (68%) had findings that explained IDA (in some patients more than one finding). Those findings were colonic polyps (n=9), carcinoma of colon (n=4), duodenal ulcer (n=4), carcinoma of stomach (n=3), colitis (n=3), atrophic gastritis (n=1), erosive gastritis (n=1) and angiodysplasia (n=1). Conclusions: High sTfR may be a good indicator of IDA caused by GIT bleeding when the ferritin level is normal or high. GIT investigation is warranted in such cases.