Pituitary-thyroid function in patients with septic shock and its relation with outcome.

OBJECTIVE

To study the time course of thyroid function abnormalities and their relation to outcome in patients with septic shock.

DESIGN

Prospective study in a cohort of consecutive patients.

SETTING

Intensive Care Unit in a University Hospital.

PATIENTS AND

METHODS

We studied 27 patients (mean age 50 +/- 19 years, Apache II score 18.4 +/- 5.2, 15 survivors) diagnosed of septic shock. Total T4 (T4) and total T3 (T3) (RIA) were determined on days 1 and 5 after admission. We also measured TSH (ultrasensitive RIA) at 08.00, 20.00 and 01.00 hours (on days 1 and 5), and the TSH response to TRH (400 microg intravenous) on days 2 and 6. Data are mean +/- SD.

RESULTS

Whereas low thyroid hormones concentrations were present on day 1 in all patients, only survivors presented a significant increase in T3 and T4 on day 5. Basal TSH levels and the area under the curve of the TSH response to TRH on day 2 were significantly higher in survivors than in non survivors (0.89 +/- 0.63 vs. 0.34 +/- 0.42 microIU/ml, and 229 + 157 vs. 101 + 101). The normal nocturnal (01.00 hr) surge of TSH (the difference between TSH concentrations at 8 am and at 1 am) was abolished in both survivors and non survivors on day 1 but it was recovered on day 5 only in survivors.

CONCLUSIONS

Our data indicate that patients with septic shock present an altered hypothalamic-pituitary-thyroid axis, and that survivors thyroid function differs from that of non survivors shortly after diagnosis. Survivors are characterised by a greater TSH response to TRH, indicating a less deranged hypothalamic-pituitary-thyroid axis. Thyroid function improves in survivors, but not in non survivors, during the course of their illness.