Use of TSH response to TRH as an independent variable.

The thyrotropin (TSH) response to thyrotropin-releasing hormone (TRH) was assessed in 35 consecutive male admissions. Patients with TSH blunting were identified; they were compared with patients without blunting and with normal subjects. Patients without TSH blunting were normal as regards all endocrine variables. Patients with TSH blunting showed reduced TSH (but normal prolactin) levels before and after TRH administration, although their thyroid hormone levels and cortisol levels were normal. Height, weight, and body surface were unrelated to TSH blunting. The test-retest reliability of a blunted TSH response was acceptable.