There are many reasons to question this paper. Not least that the research is in specific strain of mice which have had genetic modification. Doesn't necessarily invalidate the paper but does require careful assessment - more than we can achieve with the limited access.
If TSH levels such as those without thyroid issues exhibit are sufficient to make such an impact as appears to be claimed, then we need to consider many issues beyond the usual insistence that we lower our doses of thyroid hormone to achieve a TSH in - let us suggest - a range like 0.5 to 2.0.
Of course, even if that range were agreed, we have to ask whether it is likely that having four times as much TSH (at 2.0) as the lower level (0.5) is entirely acceptable. And we need to investigate with urgency whether TSH levels of 5, 10 or more have their own negative effects. Remember, we are told that many who are hypothyroid should not be treated until TSH reaches 10. Or to look at that the other way round, twenty times as much TSH as is needed
We also need to suggest that those who cannot secrete sufficient TSH should receive continuing dosing with TSH. For example, those who have pituitary issues. And question what to do in subclinical hyperthyroidism? The obvious inference being that if they are sufficiently hyperthyroid to have a low/suppressed TSH, then they would need to be treated without waiting for overt hyperthyroidism. (Though the question of which treatment is another matter.) With a similar issue arising in those who have had suppressed TSH due to overt hyperthyroidism, or relatively high doses of thyroid hormone as has long been prescribed post-cancer treatment.
Mention of the AMPK signaling pathway is also of interest because AMPK is influenced by thyroid hormone. Therefore we see that while AMPK is activated by TSH it is also increased by thyroid hormone treatment. You cannot look at the effect of TSH without also looking at the effects of thyroid hormone. Perhaps they balance out? Or it might be necessary to look at all twelve variants of AMPK?
I suggest that the worst of all worlds might occur when someone has low TSH in conjunction with low thyroid hormone levels. A state which occurs when patients are dosed by TSH alone when their TSH level, for whatever reason, fails to rise.
Also important to consider that there are numerous slightly different forms of TSH. Treating them as all having an identical effect is questionable.
TSH inhibits osteoclast differentiation through AMPK signaling pathway
Wenwen Zhang a b c d e 1, Yu Chen a b c d e 1, Yan Wang a b c d e, Yanman Zhou f, Honglin Guo a b c d e g, Jin Xu a b c d e
Received 8 January 2025, Revised 13 March 2025, Accepted 24 March 2025, Available online 27 March 2025, Version of Record 1 April 2025.
Abstract
Purpose
It is believed that osteoporosis (OP) is associated with hyperthyroidism as a result of the elevation in thyroxine levels. However, patients with subclinical hyperthyroidism, which is characterized by decreased levels of thyroid-stimulating hormone (TSH) alone, are at equal risk of osteoporosis. Research has shown that TSH receptor (TSHR) is expressed on osteoclasts, but whether TSH directly regulates osteoclasts and the underlying mechanisms remain unclear.
Methods
In this study, we used osteoclast precursor cell conditional TSHR-knockout (TSHR CKO) mouse to study the effects of TSHR knockout on bone metabolism in mice and the changes in osteoclast differentiation in vitro. Transcriptomics was used to identify differentially expressed genes and signaling pathways.
Results
In vitro, experiments confirmed that TSH inhibited osteoclast differentiation in mouse RAW264.7 monocyte/macrophage cell line and targeted the key signaling pathway AMPK by RNA-seq sequencing. We found TSHR CKO mice exhibited decreased femoral biomechanics and damaged bone microstructure. The serum levels of bone resorption marker were increased, accompanied by an increase in the number of osteoclasts.
Conclusion
TSH inhibits osteoclast differentiation by activating the AMPK signaling pathway, and exerts an osteoprotective effect. This study will provide guidance for the diagnosis and treatment of osteoporosis. TSH structural analogs or AMPK activators are expected to provide new ideas for the development of drugs to prevent and treat osteoporosis.
Limited access to abstract and a few key points:
https://www.sciencedirect.com/science/article/abs/pii/S0378111925002306