Longitudinal Evaluation of Thyroid Function in Critically Ill Surgical Patients

摘要

Thyroid hormone alterations (known as the sick-euthyroid syndrome) are common following major surgery, but the time course for appearance and recovery from these alterations has not previously been longitudinally studied in a large group of surgical patients. The authors prospectively studied 59 patients undergoing major surgery (coronary artery bypass grafting, pneumonectomy, or subtotal colectomy). Compared with preoperative values, the mean serum, T sub 4, T sub 3, free T sub 3, and TSH concentrations decreased significantly (p<0.05) following surgery. Serum reverse T sub 3 and T sub 3 resin uptake index increased, while free T sub 4 levels remained unchanged. These changes were seen within 6 hours of surgery and normalized by 1 week after surgery. Although the serum TSH response to TRH was normal before and after surgery in 56 of the 59 patients, the maximal TRH-induced increase in serum TSH and the integrated serum TSH response to TRH were suppressed in the early perioperative period. This postoperative TSH suppression correlated with elevated postoperative plasma dopamine concentrations (r = 0.57, p <0.05). Three patients with compensated primary hypothyroidism were detected in the study and represent the first documentation of serial thyroid hormone and TSH levels in hypothyroid patients undergoing major surgery. These patients had similar changes in thyroid hormone values compared with euthyroid patients. The serum TSH response to TRH was suppressed into the normal range in two of these patients on the day following surgery. The sick-euthyroid syndrome occurs within a few hours of major surgery and remits with convalescence.