Increased urinary excretion of sulfated 3,3',5-triiodothyronine in patients with nodular goiters receiving suppressive thyroxine therapy.

Abstract

Increased serum 3,3',5-triiodothyronine sulfate (T3S) levels have been detected in various pathophysiologic states. However, little is known about T3S concentrations in other biological fluids. By employing a highly sensitive, specific, and reproducible radioimmunoassay (RIA), we measured T3S in the serum and urine of 20 premenopausal women with benign nodular goiters before and after administration of thyroxine for 6 months (T4; 3.2 micrograms/kg/day). Serum T3 concentrations did not change significantly after treatment (2.0 vs. 1.7 nmol/L; p > 0.05). However, the mean serum T4 and free T4 concentrations were significantly higher after treatment (138 vs. 88 nmol/L and 28 vs. 17 pmol/L; p < 0.01, respectively). Serum thyroid stimulating hormone (TSH) levels were significantly reduced after T4 treatment (0.13 vs. 0.66 mU/L, p < 0.01) and the serum levels of T3S were significantly increased after treatment (82 vs. 45 pmol/L; p < 0.01). A good correlation was observed between increased serum T3S and T4 concentrations (r = 0.66; p < 0.001). The sulfoconjugate of T3 was significantly increased in creatinine-corrected urine after treatment (606 vs. 253 pmol/umol Cr.; p < 0.01). There was a significant correlation between increased creatinine-corrected urine T3S and increased serum free T4 (r = 0.65; p < 0.001). In summary, significant increases in serum and urine T3S levels were noted in T4-treated patients with subnormal serum TSH and borderline elevated T4. We thus conclude that the sulfation pathway may play a role in the homeostasis of thyroid hormone metabolism in T4-treated subjects with relative hyperthyroxinemia. In addition, the creatinine-corrected urine concentrations of T3S may serve as an index for the evaluation of T4-treated patients with elevated levels of T4.

• Authors: W S Huang, S W Kuo, W L Chen, M M Fuh, S Y Wu
• Journal: Thyroid : official journal of the American Thyroid Association (Thyroid) Vol. 6 Issue 2 Pg. 91-6 (Apr 1996) ISSN: 1050-7256 [Print] United States
• PMID: 8733878 (Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Iodine Radioisotopes
• Triiodothyronine, Reverse
• Thyrotropin
• Creatinine
• Thyroxine

Topics

• Adult
• Creatinine (urine)
• Female
• Goiter, Nodular (drug therapy, urine)
• Humans
• Iodine Radioisotopes
• Middle Aged
• Radioimmunoassay
• Thyrotropin (blood)
• Thyroxine (adverse effects, blood, therapeutic use)
• Triiodothyronine, Reverse (urine)