Onderzoek naar kinetiek en effecten van een enkele dosis T3

Met dit onderzoek is bekeken wat een enkele dosis T3 doet bij gezonde mensen. Het onderzoek gaat dus niet over T3 als behandeling van hypothyreoïdie. Maar om te leren wat T3 doet, is het wel nuttig om de kinetiek en effecten te bestuderen.

Single-dose T3 administration: kinetics and effects on biochemical and physiological parameters
Jacqueline Jonklaas, Kenneth D Burman, Hong Wang, Keith R Latham

Behandeling schildklier: vroeger, nu en in de toekomst
Jacqueline Jonklaas, Kenneth D Burman, Antonio C Bianco

As changes in thyroid stimulating hormone (TSH), thyroid hormones, and vital signs after administration of a single dose of liothyronine have typically only been documented for 24 hours, we documented these parameters more than 96 hours.

Methods

Blood samples were obtained for 4 days after administration of 50-mcg liothyronine to 12 healthy euthyroid participants. Concentrations of total and free triiodothyronine, free and total thyroxine, and TSH were measured. Vital signs were documented.

Results

Triiodothyronine concentrations peaked at 2.5 hours after liothyronine administration. Heart rate (HR) increased by 5 hours after liothyronine administration, subsequently reaching a value higher than baseline. Suppression of TSH concentrations began at 2 hours. The nadir TSH value at 12 hours was significantly different from baseline and remained lower than the baseline value for 2–3 days.

Conclusions

A single dose of liothyronine has both short-term and long-term effects. There is clearly a different lag time between the serum concentrations of triiodothyronine and its effects on the heart and pituitary, respectively. The increase in serum triiodothyronine concentration occurred within hours and was then followed by an increase in HR. The increased HR was transient and was followed by a reduction in TSH concentration. The suppression of TSH was delayed but was more sustained. Thus, sustained TSH reduction beyond 24 hours was achieved by a single dose of liothyronine that produced only brief increases in serum triiodothyronine levels and transient increases in HR.