[Concentrations of serum iodothyronines during starvation in genetically obese mice]

Examination of the thyroid hormones levels of genetically obese mice (ob /ob) and their lean littermates (Ob/-) revealed high concentration of 3,5,3' triiodo-L-thyronine (T3) in obese mice reflecting probably an increased of peripheral L-thyroxine (T4) deiodination to T3. During starvation, peripheral T4 metabolism is shunted from activating (T3) to inactivating pathway (3,3',5' triiodo-L-thyronine, rT3) in both groups of animals.