Thyroid function and abdominal surgery. A longitudinal study.

Surgical trauma produces complex metabolic changes and may be an excellent model for studying the effects of an acute insult on the circulating thyroid hormone concentrations. Abnormalities in thyroid function tests in patients with nonthyroidal illness can be divided into a low T3 syndrome, low T3 and T4 syndrome in more severe cases and elevated T4 syndrome. In this study 30 patients undergoing elective or urgent abdominal surgery were longitudinally evaluated with pre- and postoperative thyroid function tests. Comparing with preoperative values, a significant reduction in total T3 serum values in the immediate postoperative period was seen (p < 0.005). The rest of the variables did not show significant statistical differences between the three periods. Over half of the patients undergoing urgent surgery had a low T3 syndrome, whereas only a sixth of the patients scheduled for elective surgery suffered from this syndrome. In the late postoperative period half the patients submitted to urgent surgery persisted with alterations in thyroid function tests, whereas most of the patients scheduled for elective surgery showed an improvement in their thyroid hormone level in the same period of time. Abnormalities in thyroid hormone metabolism were more frequent in patients admitted for urgent surgery, reflecting the severity of their illness and favoring the concept that these syndromes can be used as prognostic markers.