The Claim

In mouse skeletal muscle and bone marrow cells, increasing free T4 concentrations above 10 pM progressively reduces triiodothyronine (T3) production, with T3 output dropping to zero at 50 pM, demonstrating a homeostatic downregulation of type 2 deiodinase (D2) activity that contrasts with the pituitary response.

Source: Sustained pituitary T3 production explains the T4-mediated TSH feedback mechanism.

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
18score
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.

How it works
1 study reviewed
In plain English

In mouse muscle and bone marrow cells, raising free T4 levels from 10 pM to 50 pM causes T3 production to decrease steadily until it stops completely, indicating that type 2 deiodinase activity is suppressed in these tissues at higher T4 levels.

See the scientific wording

In mouse skeletal muscle and bone marrow cells, increasing free T4 concentrations above 10 pM progressively reduces triiodothyronine (T3) production, with T3 output dropping to zero at 50 pM, demonstrating a homeostatic downregulation of type 2 deiodinase (D2) activity that contrasts with the pituitary response.

Why this might work

When thyroid hormone T4 levels rise above 10 pM in muscle and bone marrow cells, the enzyme that converts T4 into active T3 gets tagged for destruction, causing T3 production to drop to zero at 50 pM. This does not happen in the pituitary gland, where the same enzyme stays active and keeps making T3 to control hormone feedback.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Sustained pituitary T3 production explains the T4-mediated TSH feedback mechanism.

    In mouse muscle and bone marrow, too much T4 turns off the enzyme that makes T3, so T3 production stops. But in the pituitary gland, more T4 makes more T3 — the opposite happens. The study proved this exact difference.

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

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