Comparative Study on the Determination of Serum Thyroid Hormones by Two Methods of Immunoassay in Marwari Goats (Capra hircus)

The thyroid gland is the most important and largest endocrine gland for metabolic regulation. The thyroid gland is unique as it is the only tissue of the body which is able to accumulate iodine in greater quantities and combine it into thyroid hormone. A variation in blood thyroid hormone concentrations is an indirect indication of changes in thyroid gland activity; therefore, selecting a well suitable method to determine these hormones is crucial. The aim of this study was to compare serum thyroid hormone concentrations (i.e. T₄, T₃, fT₄ and fT₃) using chemiluminescence immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) methods in Marwari goats (Capra hircus). Twelve healthy male Marwari bucks of 6 months to 1 year age and weighing 18–20 kg were included in this study. They were divided in two groups, comprising 6 animal in each i.e. “CLIA group” and “ELISA group”. Collection and preservation of samples were obtained by puncturing the jugular vein with least stress to animal between 8.00 to 9.00 a.m. from “CLIA group” and “ELISA group”, respectively, by using disposable syringes. The separated serum was analysed to determine thyroxine (T₄), triiodothyronine (T₃), free thyroxine (fT₄) and free triiodothyronine (fT₃) concentrations using the mentioned methods. The data was subjected to analysis of variance (ANOVA) (Snedecor and Cochran, 1967). The critical differences among various means were worked out by “Duncun's New Multiple Range Test” (DNMRT) method. ANOVA of our data from this study indicates there was a significant difference in the T₄(P<0.0001), fT₄(P<0.01) and fT₃(P<0.05) concentrations between the two methods and that the levels of these hormones were higher when using the CLIA method, except for fT₃. The linear regression analysis of these hormones showed that the CLIA and ELISA results were significantly correlated only for fT₄ (P<0.0001) concentration. In conclusion, determination of the thyroid hormones using the CLIA method had an acceptable performance of higher sensitivity and precision and was more appropriate than the ELISA method for clinical application and investigation in Marwari goats (Capra hircus).