The Study
Deiodination of thyroid hormone by human liver.
This study looked at a single enzyme in a test tube with liver tissue, not in a real person. It tells us how the enzyme works in the lab, but not how it affects people’s health or what happens in the body.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
The liver has a special enzyme that breaks down thyroid hormones, and it works much better on some forms than others.
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 520 / 100
Quality score
Researchers compare people who have a condition (cases) with similar people who do not (controls), looking back in time for differences in exposure. Useful but more prone to bias.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means sulfation and reverse T3 are key signals the liver uses to control active thyroid hormone levels in the body.
- 2The enzyme breaks down reverse T3 400 times faster than T4 or T3, and breaks down T3 sulfate 30 times faster than regular T3.
- 3The drug propylthiouracil blocks this enzyme equally well for both reactions.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of clinical endocrinology and metabolism
Year
1988
Authors
T. Visser, E. Kaptein, O. Terpstra, E. Krenning
Related Content
Claims (6)
The thyroid hormone T4 is changed into a more active form called T3 in organs like the liver and kidneys through a biochemical process.
In human liver microsomes, deiodinase enzymes process substrates through a two-step chemical reaction that requires dithiothreitol as a cofactor, following a ping-pong kinetic pattern.
Human liver microsomes contain an enzyme that removes iodine from reverse T3 and T3 sulfate in the same way and at the same rate, indicating one enzyme performs both reactions.
In human liver tissue, reverse T3 is processed by deiodinase enzymes about 400 times faster than T4 or T3 through outer ring deiodination.
In human liver tissue, T3 sulfate is converted by deiodinase enzymes about 30 times faster than unsulfated T3, showing that the addition of a sulfate group increases the enzyme's efficiency in processing this hormone.
Propylthiouracil reduces the breakdown of reverse T3 and T3 sulfate in human liver tissue samples at similar concentrations, with an inhibition constant between 0.10 and 0.16 micromoles per liter.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.