The Study
Reciprocal changes in serum 3, 3', 5'-tri-iodothyronine concentration and the peripheral thyroxine inner ring monodeiodination during food restriction in the young pig.
This study looked at how pig livers and kidneys process thyroid hormones in a test tube when the pigs didn't eat. It found some patterns, but it didn't prove that not eating causes those changes in real life.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
When pigs don't eat enough, their liver and kidneys slow down turning one thyroid hormone (T4) into its active form (T3), but they make more of a different form (rT3) in the blood—even though the organs aren't making more of it.
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 56 / 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.
- 1This suggests that in starvation, the body may conserve energy by reducing active thyroid hormone, and rising rT3 in blood is not from more production but from slower clearance or more thyroid release.
- 2T4 to T3 conversion went down in liver and kidney; T4 to rT3 went down in liver only unless fully fasted; blood rT3 went up while organ production went down.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The Journal of endocrinology
Year
1982
Authors
A. Ślebodziński, E. Brzezińska-Ślebodzińska, R. Drews
Related Content
Claims (5)
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 growing pigs, reducing food intake leads to lower conversion of the thyroid hormone T4 into its active form T3 in liver and kidney tissue samples tested in laboratory conditions.
In growing pigs undergoing food restriction, levels of thyroid hormones T4 and T3 in the blood fall, while levels of rT3 rise, showing that the amount of rT3 in the blood does not reflect how much is being produced in tissues.
In food-restricted growing pigs, high levels of the hormone rT3 in the blood result from slower breakdown of the hormone or greater release from the thyroid gland, not from conversion of another hormone called T4.
In growing pigs, limiting food intake reduces the conversion of thyroxine to rT3 in the liver but not in the kidneys, unless the pigs are completely deprived of food, showing that these two tissues regulate this metabolic process differently during energy shortage.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.