ABSTRACT
Patient with critical illness has disturbed thyroid function tests sick euthyroid syndrome' in the form of low total and free T 3, T 4 [FT 3, PT 4] and low level of the serum TSH. We investigated the hypothalamic-pituitary-thyroid axis and its relation to the mortality and/or morbidity before and after TRH stimulation. Bas-line serum TSR, free T 3, T 4 and after 200 microgram TRH, stimulated serum TSR, free T 3,and free T 4, were measured in 17 patients presented with acute critical illness, in 24 patients with chronic illness and in 20 healthy control. The results showed significant reduction in baseline and impaired secretion of thyroid hormones [FT 4 and PT 3] as well as TSH level in patients groups compared to control group. In acutely ill patients this reduction is mainly in PT 3, while in chronic patients reduction of both FT 3 and FT 4 were evident. A bolus I.V. injection of TRH in critically ill patients leads to marked increases in the serum TSR without changes in serum FT 3 or FT 4 and outcome of patients. It was found that serum TSH, FT 4 and serum albumin were correlated significantly with the mortality and morbidity of critically ill patients than APACHE II score inspite of its long term used in the prediction of morbidity and mortality in such patients. However follow up measurements of FT 4 and TSH can take it as a marker of recovery of critical illness. The results demonstrated an impairment of the hypothalamic-pituitary-thyroid axis in patients with critical illness and serum levels of FT 4 and TSH can be used in the prediction of morbidity and mortality in such patients