[Evolution of serum gammaglutamyl transpeptidase activity in treated hyperthyroid and hypothyroid patients]

The pattern of gammaglutamyl transpeptidase levels was studied in the sera of 25 subjects with hyperthyroidism and 11 subjects with hypothyroidism, before and after treatment, and in 14 age- and sex-matched control subjects. Gammaglutamyl transpeptidase levels were significantly increased in hyperthyroidism (65 +/- 59 U/l) (p less than 0.01) and significantly decreased under treatment (40 +/- 27 U/l) (p less than 0.001). Before treatment, gammaglutamyl transpeptidase levels correlated with alkaline phosphatase levels and 5'-nucleotidase levels, the correlation persisting after treatment with 5'-nucleotidase. Alkaline phosphatase levels significantly increased under treatment (p less than 0.01). The percentages of gammaglutamyl transpeptidase variation correlated with thyroxine (r = 0.44, p less than 0.03), triiodothyronine (r = 0.47, p less than 0.02) and latent fixation capacity (r = 0.44, p less than 0.03) variations. Subjects with hypothyroidism had significantly decreased gammaglutamyl transpeptidase levels before treatment (18 +/- 9 U/l, p less than 0.01). Alkaline phosphatase levels were significantly decreased before treatment, and significantly increased after treatment. For all subjects with hyperthyroidism of hypothyroidism, the percentages of gammaglutamyl transpeptidase variations correlated with thyroxine (r = 0.48, p less than 0.003) and triiodothyronine (r = 0.39, p less than 0.016) variations. These results suggest that variations in gammaglutamyl transpeptidase levels in hyperthyroidism and hypothyroidism are, at least in part, in relation with variations in thyroid hormone levels.