The diagnosis of iron deficiency anemia (IDA) in the elderly is difficult because of the prevalence of chronic diseases, which can cause anemia with high ferritin levels, even in the presence of iron deficiency. Therefore, we studied the sensitivity and specificity of a serum transferrin receptor assay, which is not affected by chronic diseases, in the diagnosis of IDA in elderly patients.
We performed a prospective controlled study of 49 consecutive male and female patients older than 80 years who were admitted to an acute geriatric department. Bone marrow aspirate confirmed IDA in all 49 patients. Fourteen additional patients, also older than 80 years, with anemia but without evidence of iron deficiency on results of bone marrow examination, served as a control group. All patients underwent evaluation by means of a detailed medical history and results of complete physical examination, routine blood tests, and specific tests for diagnosis and evaluation of anemia. Examination of bone marrow aspirate was performed for all patients. Levels of transferrin receptor in serum were determined by means of a specific enzyme-linked immunosorbent assay. The transferrin receptor–ferritin index (TR-F index) was defined as the ratio of serum transferrin receptor level to log ferritin level.
Only 8 patients could be diagnosed as having IDA by means of routine blood test results (serum iron, ferritin, and transferrin saturation levels). In contrast, the TR-F index disclosed IDA in 43 of the 49 patients, thus increasing the sensitivity from 16% to 88%.
The diagnosis of IDA in the elderly by means of routine blood tests has a very low sensitivity. The TR-F index is much more sensitive, and when results are positive, the TR-F index can eliminate the need for bone marrow examination.