An Experimental Study of Pathological Changes of Thyroid after Severe Burns and Their Mechanisms in Rats / 第三军医大学学报

ABSTRACT

Thirty percent TBSA full thickness burns due to napalm was inflicted to the rats and the pathological changes of the thyroid were studied under optical and electron microscopy and with peroxidase histochemistry for 15 days. The alterations of serum T3 and T4 levels accompaniying the pathological changes were also observed dynamically.It was found that the pathological changes of the thyroid could be distinguished into three phases as follows.1. The phase of injury inhibition. This phase existed from the 2nd to the 24th hour postburn and was characterized by marked damage on the follicular epithelium.2. The phase of structural and functional recovery. This phase entended from the 3rd to the 6th day postburn. In this phase, the damages on the thyroid became abated and its damaged structure showed a tendency to recover.3. The phase of active function. It extended from the 10th to the 15th day postburn. The organelles to synthesize and release thyroid hormone were fonud well developed.The alteration of T4 run parallelly to the pathological changes of the thyroid in all the stages, while T3 level was continously inhibited because of the lower serum concentration of T4, the metabolic disturbance of T4 deiodination, and the inhibition of thyroid secretion in the early postburn stage and the metabolic disturbance of T4 deiodination in the middle and late postburn stages. In the early postburn stage, the inhibition of thyroid peroxidase was an important factor of functional inhibition of the thyroid.