Thyrotoxicosis is a hypermetabolic state caused by elevated levels of free T3 and T4 in the blood, acting in nearly all body tissues. In this study, livers of rats treated with supraphysiologic doses of T4 (20µg/100g of body weight) for 20 days, and that had significantly increased serum T4 (p=0.02), were analyzed by stereologic methods. The treated rats lost body weight, while the control group did not (p=0.10), and their liver weight increased (p=0.08). The non-lobular parenchyma proportion was decreased in the T4-treated rats; thus, lobular parenchyma was significantly increased (p=0.05). The Kupffer cell volumetric fraction in the lobular parenchyma was significantly lower (p=0.05) than in controls. There was a significant hepatic glycogen depletion in the lobular parenchyma, as compared with the control group (p=0.008). In conclusion, thyrotoxicosis induces hyperplasia and/or hypertrophy of the hepatic cells, with reduction of the energy reserve.
Hypertyroidism; Morphometry; Liver; Glycogen; Rats
