The aim of this study is to investigate trace element levels (Cr, Cu, Fe, Mg, Mn, Se, Zn, As, B, Si and Co) in serum samples of patients with papillary thyroid cancer. The analysis of trace elements levels of samples carried out using ICP-OES. Elements in blood samples were determined by ICP-OES after using Hettich Universal Centrifuge and differences between the values of Zn, Mg, Fe and Cu of blood samples were obtained pre -therapy and post -therapy. The concentrations of elements were normalized to percentage. Later, electron densities (N-el) of blood samples have been determined using ZXCOM program. A venture was made to perform a correlation between electron density and pre -posttreatment. This attempt is quite new in literature. Interestingly, it was generally observed that the electron densities of blood samples posttreatment are higher than pretreatment. Among elements, normalized concentration values of Cu and electron densities were in particular compared with patient type. Also, statistical analysis of blood results was achieved for 11 patients and 11 normal individual as control group for pre-posttreatment. Wilcoxon test which is a non -parametric test was used. 2016 Elsevier Ltd. All rights reserved.