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Updated: Aug 26, 2025
Author Spotlight: In Vivo Assessment of Thyroid Hormone Disruption Using the THAI Mouse Model
Published on: October 6, 2023
Intraday Changes and Clinical Applications of Thyroid Function Biomarkers in Healthy Subjects
Yan Zhang1, Hua-Li Wang1, Chao-Qiong Zhou1
1Department of Clinical Laboratory, Traditional Chinese Medicine Hospital of the Pidu District, Chengdu, China.
Objective:
We evaluated the intraday changes of thyroid function biomarkers in healthy subjects to help clinicians diagnose thyroid diseases in appropriate timing.
Methods:
Blood samples were collected from 31 subjects at 0:00, 4:00, 8:00, 12:00, 16:00 and 20:00 on the sampling day and analyzed for thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free T3 (FT3), and free T4 (FT4). The intraday concentration changes were analyzed using Friedman's 2-way analysis of variance by ranks.
Results:
The concentrations of TSH, T3, T4, FT3, and FT4 in males were significantly higher than those in females (P < .01). The obvious peak circadian rhythm of TSH was observed at 0:00 AM with gradual decline thereafter, whereas other biomarkers showed no rhythmic changes.
Conclusion:
Sex differences should be considered in interpreting thyroid function tests. It is important to select the sampling time according to the clinician's diagnostic needs, especially at night when TSH secretion peaks.
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