Objective: To compare measurements of thyroid and adrenal function between survivors and non-survivors in critical illness.
Design and setting: Prospective, observational study at the medical/surgical intensive care unit (ICU) at Royal Infirmary of Edinburgh, Scotland.
Patients: 163 patients admitted to the intensive care unit over a 4-month period.
Interventions: We took blood samples within 1 h of ICU admission, and at 08:00 hours on the subsequent 2 days of ICU admission. We measured serum total (TT(4)) and free (fT(4)) thyroxine, total (TT(3)) and free (fT(3)) tri-iodothyronine, thyrotropin (TSH) and plasma cortisol concentrations.
Measurements and results: TT(3) and TT(4) concentrations were significantly less in non-survivors than in survivors on admission and on day 1 but not on day 2. Cortisol concentrations were higher in non-survivors on admission and on day 1 but not on day 2. TSH, fT(3) and fT(4) concentrations did not differ significantly between survivors and non-survivors at any time. Only TT(4) and cortisol were independent predictors of outcome. Prediction of outcome from the admission sample values was not better than using APACHE II scoring.
Conclusions: Thyroid hormone and cortisol concentrations differ between survivors and non-survivors on admission to intensive care, but the values overlap. These differences do not allow accurate prediction of outcome from critical illness.