[Diagnosis of iron deficiency: evaluation of the "soluble transferrin receptor/transferrin" ratio].

OBJECTIVE: This study was aimed at determining the diagnostic value of conventional laboratory tests regarding the iron status and serum transferrin receptor in hospitalized patients.
METHODS: Patients who had to undergo bone marrow aspirate examination were included in this 8-month prospective study. Iron deficiency was defined as the absence of stainable iron on bone marrow examination. Patients with stainable iron were included in the control group. The higher value of diagnostic efficacy determined the cut-off value for each parameter of the iron status.
RESULTS: Twenty-one patients (17 females, four males) (mean age: 52 years) with iron deficiency and 33 control subjects (20 females, 13 males) (mean age: 60 years) were included in the study. The ratio serum transferrin receptor/serum ferritin had the best diagnostic efficiency (78%) with a sensitivity of 81% and a specificity of 97%. Serum ferritin alone with a cut-off value of 60 micrograms/L had the same specificity (97%) but a lower sensitivity (76%). The diagnostic value of all other analyzed tests was below 66% (transferrin alone, mean corpuscular volume, transferrin saturation, iron, serum transferrin receptor alone, red cell distribution width).
CONCLUSION: Among in-patients, ferritin remains the first intention test to diagnose iron deficiency, but the cut-off value should be increased (60 micrograms/L in this study). The ratio "serum transferrin receptor to serum ferritin" provides the highest specificity with a higher cost and should be used only in doubtful cases.