The non-thyroidal illness syndrome after coronary artery bypass grafting: a 6-month follow-up study

The non-thyroidal illness syndrome (NTIS) is considered a transient and completely reversible phenomenon, but it has been shown that it may last for several days postoperatively after coronary artery bypass grafting (CABG) surgery. This study was undertaken to assess thyroid function 6 months after uncomplicated CABG. The thyroid profile was evaluated in 40 consecutive patients undergoing CABG preoperatively, at 0, 12, 48, and 120 h postoperatively, and at 6-month follow-up. Triiodothyronine (T3), free T3 (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) were assayed using a microparticle enzyme immunoassay. T4 and total serum thyroid hormone-binding capacity (T-uptake) were measured on the same samples using a fluorescence polarization immunoassay. Patients with severe systemic illness and patients treated with amiodarone were excluded. All patients were euthyroid at admission. Mean age was 67.4+/-9.0 years. There were 31 (77.5%) men. Typical NTIS was observed in all patients, and the FT3 concentration was still reduced by postoperative day 5 (p