The Study
Euthyroid Sick Syndrome Precipitated By Rapid Weight Loss Following Semaglutide Initiation: A Case Report
This story is about one person who lost weight quickly and then had weird blood test results. It doesn't prove that the weight-loss medicine caused it — it just shows that it happened in one person at the same time. We can't say it will happen to others.
Analysis score
Maximum 30 for a case report.
Where the score came from
When you lose weight very quickly, your body slows down its metabolism to save energy — and one way it does this is by changing thyroid hormone levels, even though your thyroid gland is fine.
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 530 / 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.
- 1Yes — this means abnormal thyroid tests during fast weight loss often don’t mean you have a thyroid disease; they’re just your body adapting.
- 2A woman lost 22 kg (18%) in 4 months on semaglutide; her T3 dropped, T4 stayed low-normal, TSH stayed normal — all signs of a body conserving energy.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Clinical Medicine Insights. Endocrinology and Diabetes
Year
2026
Authors
Ziad W. Elmezayen, Farah Qrareya, Abdallah Abdallah, Hossam Salameh, W. Qaisi
Related Content
Claims (7)
When the body experiences low energy availability or extreme stress, it converts more thyroxine into reverse T3, which lowers the metabolic rate.
During rapid weight loss, thyroid hormone levels change to show low free T3, low-normal free T4, and normal or low TSH without any thyroid disease, and these changes return to normal when weight stabilizes and nutrition improves.
During rapid weight loss, changes in thyroid blood test results often reflect normal body adjustments and do not indicate disease; these changes should be evaluated with clinical symptoms and metabolic markers.
Semaglutide-induced rapid weight loss reduces the liver's production of the active thyroid hormone T3 and increases the production of the inactive form rT3, altering thyroid hormone metabolism in a pattern associated with euthyroid sick syndrome.
When people lose weight quickly using GLP-1 receptor agonists and consume too little protein, their bodies experience increased muscle breakdown and develop a specific metabolic state known as euthyroid sick syndrome.
Obese adults who lose 18% of their body weight over four months develop a specific pattern of thyroid hormone changes: low T3, normal-low T4, and normal TSH, which is a physiological response to severe calorie restriction and not a sign of thyroid disease.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.