Thyroid hormone levels in the developing obese-hyperglycemic syndrome.

Examination of the thyroid hormone levels of C57BL/6J ob/ob mice and their lean littermates between the ages of 6 days and 22 weeks revealed that obese mice have significantly reduced hormone concentrations between 10 and 21 days of age. Thereafter, the values remained equal to, or above those or their lean littermates. The present data indicate that the hypometabolism and abnormal thermal regulation of weanling mice could be a result of diminished thyroid hormone levels, but that other mechanisms must be responsible for the persistence of these abnormalities in adult ob/ob mice.