The Study
Extrathyroidal effects of propylthiouracil and carbimazole on serum T4, T3, reverse T3 and TRH-induced TSH-release in man.
This study watched what happened to 19 people’s thyroid hormones when they took a medicine called PTU. It saw that some numbers changed, but it didn’t compare them to people who didn’t take the medicine or control for other things. So we can’t say the medicine caused the change — just that they happened together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Doctors gave two different drugs to people on thyroid hormone replacement to see if they changed how the body processes thyroid hormones.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 527 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The change in T3 and reverse T3 with PTU suggests it alters how the body converts thyroid hormones outside the thyroid gland, which could affect metabolism.
- 2When patients took PTU, their active thyroid hormone (T3) dropped from 90 to 79, and their inactive hormone (reverse T3) rose from 51 to 58.
- 3Carbimazole changed nothing.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Acta endocrinologica
Year
1978
Authors
K. Siersbæk-Nielsen, C. Kirkegaard, P. Rogowski, Jens Faber, B. Lumholtz, Th. Friis
Related Content
Claims (3)
The body converts the thyroid hormone T4 into two different forms: T3, which increases metabolic rate, and reverse T3, which does not. The relative amounts of these two forms determine how active metabolism is.
In patients with severe hypothyroidism taking levothyroxine, adding carbimazole does not change the blood levels of T3, reverse T3, T4, basal TSH, or TSH released after TRH stimulation.
In patients with severe hypothyroidism taking levothyroxine, adding propylthiouracil lowers serum triiodothyronine (T3) levels and raises reverse T3 levels, demonstrating a direct effect on how the body converts thyroid hormones outside the thyroid gland.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.