The Claim

During food restriction in growing pigs, serum concentrations of thyroxine (T4) and 3,5,3'-tri-iodothyronine (T3) decrease, while serum concentration of 3,3',5'-tri-iodothyronine (rT3) increases, indicating a dissociation between serum rT3 concentration and its peripheral production rate.

Source: Reciprocal changes in serum 3, 3', 5'-tri-iodothyronine concentration and the peripheral thyroxine inner ring monodeiodination during food restriction in the young pig.

What the research says

Roughly balanced

Support and challenge are close. The picture may shift as more studies come in.

Supports
6score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Description
1 study reviewed
In plain English

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.

See the scientific wording

During food restriction in growing pigs, serum levels of thyroxine (T4) and 3,5,3'-tri-iodothyronine (T3) decrease while 3,3',5'-tri-iodothyronine (rT3) increases, indicating a dissociation between serum rT3 concentration and its peripheral production rate.

Why this might work

When food intake drops, the liver and kidneys slow down their ability to convert the main thyroid hormone into its active form, causing less active hormone to circulate. At the same time, the body stops breaking down the inactive form of the hormone as quickly, so it builds up in the blood. The thyroid gland may also release more of this inactive form, adding to the rise in blood levels even though the liver and kidneys aren't making more of it.

Verified mechanismbased on 1 study

What the research says

1 study

  1. 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.

    When young pigs eat less, their bodies make less of the active thyroid hormone (T3) but more of an inactive form (rT3)—even though their liver and kidneys aren’t making more of it. This means the extra rT3 in the blood must be coming from somewhere else, like the thyroid gland or slower breakdown.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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