Thyroid function after thermal trauma

The thyroid function was analyzed for 4-6 weeks in a prospective study of 12 thermally injured patients. The burn size range was 15-90%. Serum concentrations of 3,5,3'-triidothyronine (T3) was suppressed and 3,3',5'-triidothyronine (rT3) was increased. The ratio T3/rT3 was subnormal on the third day after the trauma and normalized after 3 weeks. Thyroxine and the free T4-index were within the normal range. The free T3-index were within the normal range. The TSH concentration was initially low but slowly increasing during the period of study. The concentration of the thyroxine-binding globulin (TBG) varied within the normal range. The T3 resin uptake test varied inversely with the TBG concentration. The concentration of thyroxine-binding prealbumin (TBPA) was subnormal. A control experiment excluded possible interference on the hormone concentrations of administered donor blood and plasma. It is concluded that the thyroid hormones are not responsible for the posttraumatic hypermetabolism in burn injury. The present findings further indicate a depletion of metabolically active thyroid hormones at the cellular level after burn injury.