"The low T3 syndrome" and impaired thyroid protein synthesis in experimental trauma

The thyroid response was evaluated in the present trauma model. Trauma of varying severity was studied in 3 groups of anesthetized pigs. The animals were exposed to preparative surgery alone (n = 6) or followed by a standardized missile trauma to a hind leg (n = 10) or to the abdomen (n = 8). Post-trauma observation for 24-48 hours under continuous anesthesia included measurements of circulating T4, T3 and rT3. The serum concentrations of T4 and T3 fell significantly in all groups, the fall being exponential in the missile trauma groups. The reductions were greatest in the most severely injured group (abdominal trauma) and least in the group with preparative surgery only. The nadir of T4 concentration was reached at 24 hours in all groups. The T3 nadir occurred at 12 hours in the abdominal trauma group and at 24 hours in the groups with hind-leg trauma and preparative surgery. The rT3 concentration was significantly increased in the missile trauma groups. Thyroid protein synthesis was analysed in vitro by incubating thyroid tissue from pigs with missile trauma (n = 9) or with preparative surgery (n = 6). The 3H-leucine incorporation into the soluble thyroid proteins, measured as DPM/DNA, was 35% lower after missile trauma than after preparative surgery.(ABSTRACT TRUNCATED AT 250 WORDS)