TSH responses to two TRH doses in men with Alzheimer's disease

TSH responses to two TRH doses (0.1 mg, 0.5 mg) were determined in 10 men with Alzheimer's disease (AD) and in nine healthy matched controls. Maximum change in TSH (delta TSH) and TSH responses over time, analyzed independently for each TRH dose, did not reveal any significant differences between the AD and the normal subjects. Blunted delta TSH responses were an uncommon finding in both groups. Analyses examining the influence of TRH dose on TSH responses revealed significant group differences. In normal subjects, delta TSH responses following the 0.5 mg TRH dose were significantly greater than delta TSH responses following the 0.1 mg TRH dose (p less than 0.01). However, in the AD group, the effects of TRH dose on delta TSH were largely attributable to the exaggerated and outlying TSH responses of one AD subject. For the remaining nine AD subjects, delta TSH responses following the 0.1 mg and 0.5 mg TRH doses were not significantly different (p greater than 0.1). In the analysis of TSH responses over time, the difference between the 0.1 mg and the 0.5 mg TRH-induced TSH responses was significantly smaller in the AD group at several timepoints after infusion compared to the normal subjects.