2.2. Analysis of Serum-Ferritin (S-Fe), Serum-Iron, S-Total Iron Binding Capacity (S-TIBC) and Serum-Transferrin Saturation (S-TSAT) in Blood

Serum concentration of S-Fe, S-Iron and S-TIBC were measured, and S-TSAT were estimated (S-Iron/S-TIBC × 100) to evaluate iron status. The participants provided a non-fasting blood sample. Blood for serum analysis (S-Fe, S-TIBC, S-Iron, S-TSAT) was collected in a 5.0 mL tube (BD vacutainer SST II advance, Becton Dickinson, Franklin Lakes, NJ, USA). The tubes were mixed gently by five inversions and placed in a rack. The blood samples were stored at room temperature before centrifugation at 1500 rpm for 10 min (centrifuge model 5804, Eppendorf, Hamburg, Germany). The samples were centrifuged after 30 to 120 min, then separated immediately. Thereafter, all samples were refrigerated (4 °C) until analysis within three days at the Fürst medical laboratory (Oslo, Norway). The assays were performed with ADVIA Centaur XP System and XPT System by immunoassays using chemiluminescence technology, Erlangen, Germany.