The Study of TSH Surge in Apparently Euthyroid Obese Individuals and Its Link to Leptin

Document Type : Original Article

Authors

1 The Department of Internal medicine ,endocrinology and diabetes unit , Faculty of Medicine, Ain Shams University,

2 The Department of Internal medicine ,endocrinology and diabetes unit, Faculty of Medicine, Ain Shams University

3 The Department of Internal medicine, endocrinology and diabetes unit, Faculty of Medicine, Ain Shams University,

Abstract

Background: There is a complex link between obesity and thyroid hormones. Thyroid Stimulating Hormone (TSH) normally shows a nocturnal surge in euthyroid individuals which, if blunted, may indicate a subtle thyroid dysfunction. Aim: Our target was to study the TSH surge in euthyroid participants with obesity and explore its link with leptin levels.

Methods: We conducted our pilot cross-sectional study on 60 euthyroid obese patients. Patients with primary or secondary hypothyroidism or those taking levothyroxine were excluded. Patients with severe acute illness, depression, renal, hepatic and cardiac disease were also ruled out. For all participants we recorded TSH at 10 am, 7pm, and 10 pm to determine its peak and nadir levels to express the TSH surge as percent rise over nadir [(peak TSH - nadir TSH) × 100] / nadir TSH. TSH surge was considered blunted if below 50 % rise above nadir (normal 50- 300%). Leptin and glucose parameters were investigated.

Results: 13.333% participants had blunted TSH surge with mean TSH at 10 am 4.240± 0.910, 7pm 3.805±0.835 and 10 pm 5.040 ±1.143. All participants were divided into a group with blunted TSH surge and another group with normal TSH surge. Comparing the two groups a significant difference was detected regarding HbA1c not leptin. In patients with a blunted TSH surge, TSH surge was not correlated to leptin yet correlated to HbA1c.

Conclusion: Our study showed that 13.333% of euthyroid obese patients had a blunted TSH surge. Further studies are needed to establish a causal effect relationship.

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Zagazig University Medical Journal
Volume 31, Issue 10
October 2025
Pages 5044-5049

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