The Study
An Abnormality of Thyroid Hormone Receptor Expression May Explain Abnormal Thyrotropin Production in Thyrotropin-Secreting Pituitary Tumors
This study looked at a few people with a rare tumor and noticed their thyroid hormone receptors were missing, even though the instructions to make them were still there. It doesn't prove the missing receptors caused the tumor — it just found them together.
Analysis score
Maximum 58 for a case-control study.
Where the score came from
The body usually stops making thyroid hormone when there's enough, but in these rare tumors, it keeps making too much TSH even when thyroid hormone is high.
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 527 / 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 could explain why patients have high thyroid hormone levels without the body turning off TSH production.
- 2Tumors had normal thyroid hormone receptor genes (mRNA) but no receptor proteins; normal pituitaries had both.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Thyroid
Year
1998
Authors
N. Gittoes, Christopher McCabe, J. Verhaeg, M. C. Sheppard, J. Franklyn
Related Content
Claims (8)
When thyroid hormone levels rise in the blood, the pituitary gland reduces its production of thyroid-stimulating hormone (TSH).
When thyroid hormone levels in the blood are high, the pituitary gland reduces production of thyroid-stimulating hormone. When thyroid-stimulating hormone levels are low, the thyroid gland produces thyroid hormones without normal regulatory control.
TSH-secreting pituitary tumors do not contain thyroid hormone receptor proteins in the cell nucleus, even though the genetic instructions to make these proteins are present, which disrupts the normal feedback mechanism that controls hormone production and allows the tumor to grow unchecked.
In tumors that produce excess thyroid-stimulating hormone, the genetic instructions for thyroid hormone receptors are present and normal, but the receptors themselves are not made, showing a failure in the process that converts genetic instructions into proteins.
In certain pituitary tumors that produce too much TSH, the absence of thyroid hormone receptors prevents thyroid hormone from turning off TSH production, resulting in high levels of both thyroid hormone and TSH.
In tumors that produce excess TSH hormone, the proteins that respond to thyroid hormones are not detectable, even though the genetic instructions to make them are present. This suggests a problem in converting those instructions into functional proteins, which could disrupt the body's normal control of TSH levels.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.