title: Effect of a single oral dose of L-thyroxine (150 micrograms) on serum thyroid hormone and TSH concentrations in clinically euthyroid goitrous patients.
abstract: Serum TT4, FT4, TT3, FT3 and TSH, concentrations were measured before and 0.5, 1, 2, 3, 4, 5 hours after a single oral dose of L-T4 (150 micrograms) in 21 clinically euthyroid goitrous patients on a long-term therapy program. The mean basal TT4 concentration, 8.85 +/- 0.52 micrograms/dl (mean +/- se), increased significantly at the second hour (10.04 +/- 0.52 micrograms/dl, p < 0.001) and reached the highest value at the third hour (10.35 +/- 0.55 microgram/dl, p < 0.001). Subsequently the mean serum TT4 concentration remained elevated until the fifth hour (10.20 + 0.60 microgram/dl, p < 0.001). The mean basal value of FT4 concentration, 8.66 +/- 0.40 pg/ml, increased significantly at 30 minutes (9.19 +/- 0.40 pg/ml, p < 0.01) and reached the highest value at the third hour (11.81 +/- 0.56 pg/ml, p < 0.001). The mean basal serum FT3 concentration, 3.56 +/- 0.10 pg/ml, increased significantly 30 minutes (3.72 +/- 0.11 pg/ml p < 0.05) after L-T4 administration; the mean serum FT3 concentration was significantly higher than the basal level and 1 and 2 hours as well, and reached the highest value at the third hour (3.86 +/- 0.09 pg/ml). The mean serum TT3 concentration did not show any significant change at any time. The mean basal TSH value (2.73 +/- 0.42 microUI/ml) declined progressively. At 30 minutes it decreased significantly (2.29 +/- 0.38 microUI/ml, p < 0.01) and reached the lowest value at the fifth hour (1.39 +/- 0.26 microUI/ml, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Medical Clinic II, University of Pisa, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Carpi
authors.forename: M G
authors.initials: MG
authors.lastname: Toni
authors.forename: C
authors.initials: C
authors.lastname: De Gaudio
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006042:Goiter / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D015592:Immunoradiometric Assay; D008875:Middle Aged; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine