Increased alpha-subunit response coexist with increased TSH response to TRH test in healthy individuals.

OBJECTIVE: The alpha-subunit (Alpha-SU) response to TRH was studied to examine the response of alpha-SU under TRH stimulation in normal situation.

METHODS: Thirty seven healthy individuals were included in the study. They were divided into two groups according to the data taken: A with TSH equal or more than seven fold the basal values (0: 3.14+/-1.2 microU/ml., 30 after TRH: 20.22+/-4.6 microU/ml) and B with TSH 2 to 6 fold the basal values (0: 0.5+/-0.1 microU/ml., 30 after TRH: 2.9+/-0.5 microU/ml). Both groups exhibited similar FT3 and FT4 levels.

RESULTS: In group A, prolactin displayed a 3 fold increase from the basal values, whereas alpha-SU increased 4 fold with a difference being statistically significant (p<0.001). In contrast, in group B individuals neither prolactin nor alpha-SU exhibited any significant difference from the basal values.

CONCLUSION: The expression of alpha-SU upon TRH stimulation is dependent on the TSH basal values.