Diagnostic Accuracy of Serum Iron and Total Iron Binding Capacity (TIBC) in Iron Deficiency State.

OBJECTIVE: To determine the diagnostic accuracy of serum iron and total iron binding capacity (TIBC) in detection of iron deficiency.

STUDY DESIGN: Descriptive, analytical study.

PLACE AND DURATION OF STUDY: Department of Chemical Pathology and Endocrinology, from January 2013 to October 2015.

METHODOLOGY: Data of 1,815 patients with results of serum iron, TIBC and ferritin from January 2013 to October 2015 was retrieved from Laboratory information System (LIMS) of AFIP. Diagnostic Accuracy Studies (STARD) guidelines were followed. Subjects of either gender, aged 1 - 68 years were included. Cases with raised serum ferritin levels (male > 336 ng/ml, female > 307 ng/ml) were excluded. Serum Ferritin was taken as gold standard with specificity of 99% and sensitivity of 80% at concentration of 30 ng/ml. Transferrin saturation was determined by dividing serum iron by TIBC and multiplying by 100.

RESULTS: Out of 1,815 subjects, 931 (51.29%) were males and 884 (48.71%) were females. The median age of the patients were 29.1 years (Inter-quartile range, IQR 19.1). Taking ferritin as gold standard, the sensitivity and specificity of serum iron was 63.5% and 38.6%, respectively; while that of TIBC was 64.5 % and 42.8%, respectively. Ferritin showed poor correlation with iron, TIBC and transferrin saturation.

CONCLUSION: Serum iron and TIBC give no additional information in the diagnosis of iron deficiency anemia and these tests are redundant for the diagnosis of iron deficiency state, if serum ferritin is available.