Comparison of measurement of serum tsh by two 3rd generation techniques.

Abstract

The present study compared the measurement of serum TSH by two 3 rd generation methods based on different principles i.e. Chemiluminesence (CLIA) and Fluorometric enzyme immuno-assay (FEIA). Main aim of the study was to evaluate the usefulness of the more sensitive assay method in patients with thyroid disease and non-thyroid illness (NTIs). Blood samples were withdrawn randomly from 125 subjects attending OPD and same sample was analyzed for TSH on two equipment’s based on methods with different principles.i.e. CLIA (Chemiluminesence) and FEIA (AIA-360). Out of 125 serum samples, the levels of TSH were within normal range in 68 subjects, were above normal range in 35 subjects and were below normal range in 22 subjects by both the methods. A specific value for TSH could not be reported by FEIA based equipment-AIA-360 in 14 (63.6%) out of total 22 hyperthyroid subjects taken up for the study. The TSH values in 35 hypothyroid subjects obtained by two different method was also significantly (p< 0.0001) different. This clearly indicates that the Chemiluminesence assay system is far superior with respect to precision and sensitivity as compared to FEIA for reporting subnormal TSH levels as well as above normal TSH and can be useful in detection of SCTDs (subclinical thyroid dysfunction) and in screening of thyroid diseases.