Biological variation in thyroid function tests in older adults and clinical implications
Authors' conclusion
CVI for TT4 and TT3 was halved in older compared to younger adults with two tests of TT4 needed to describe the individual set-point. Similar CVI between older adults caused TT4 to provide a reliable estimate of thyroid function, and the added value of measuring thyroxine could improve clinical practice.
Study context
- Population
- Older adults without thyroid disease vs previously studied euthyroid younger men
- Participants
- 19 vs 15
- Comparison
- Older adults vs younger adults
- Older adultsn = 19
- Younger adultsn = 15reference
- Outcome
- CVI
- Follow-up
- 1 year
Methodological detailsmonthly blood sampling for 1 year, single-batch analysis in random order
- Monthly blood sampling for 1 year
- Single-batch analysis in random order
Main finding
As reported in the abstract
- CVI for TSH, older/younger adults
- 19.0%/25.4%
- CVI for total thyroxine (TT4), older/younger adults
- 5.5%/10.8%
- CVI for total triiodothyronine (TT3), older/younger adults
- 6.9%/13.2%
- TT4 in older adults: only parameter with comparable CVI between individuals
- p = .22
Further findings
Interindividual CV
- TSH, older/younger adults
- 46.7%/44.0%
- TT4, older/younger adults
- 12.7%/19.5%
- TT3, older/younger adults
- 14.6%/22.4%
Index of individuality
- Below 0.6 for all hormones in all age groups
Samples needed to determine homoeostatic set-point at 10% precision in older adults
- TSH
- 14-21
- TT4 and TT3
- 2
Original publication
Biological variation in thyroid function tests in older adults and clinical implications. Clin Endocrinol (Oxf). Published 18 September 2023. doi:10.
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