Thyroid function tests in elderly patients with and without an acute illness.

Thyroid function was assessed by measurement of free thyroid hormones and thyrotrophin (TSH) in 78 acutely ill elderly patients and in a control group without acute illness. Abnormal results with any test were more frequently found in the acutely ill group than in controls. In particular, abnormal TSH values were found in 40% of the acutely ill group and in only 8% of controls (p less than 0.001). Seven acutely ill subjects had very low TSH levels (less than 0.04 mU/l) and a blunted response to thyroid-releasing hormone (TRH). With few exceptions these abnormalities could not be attributed to thyroid disease. This suggests that pituitary TSH secretion can be impaired in euthyroid sick old people. High sensitivity TSH assays may therefore be inappropriate as first-line tests of thyroid function, at least in this select group.