Comparison of different methods for iodothyronines extraction from animal tissues

Four different methods for thyroid hormones concentration in various tissues have been compared. The methods involve homogenization, extraction with 95% ethanol and assay of iodothyronines by a highly sensitive RIA. The method described by Chopra et al. has been selected and used for further estimations as the most reliable and convenient for a continuous laboratory work. The T4 levels (means +/- SE) found in the liver, kidney and skeletal muscle were 22.49 +/- 2.19, 14.89 +/- 1.56 and 8.33 +/- 1.73 ng per g wet tissue. The T3 contents were 8.53 +/- 1.08, 9.52 +/- 0.69 and 4.90 +/- 0.76 ng per g wet tissue, respectively.