Send at ambient temperature to the laboratory. If unavoidable, samples can be stored refrigerated overnight.
Relevant clinical details including whether for diagnosis or follow up. Current treatment especially T4 replacement, anti-thyroid drugs, post thyroid surgery, radioiodine or amiodarone and any history or suspicion of pituitary disease.
The department has a specific testing strategy for Thyroid Function Testing that is based on NICE guidance. This strategy can be found here: GHNHSFT Clinical Biochemistry Thyroid Testing Strategy.pptx
The assays are run throughout the day and night.
The in-lab turnaround time is normally less than 24 hours.
The test can be ordered as an urgent request.
Adult Reference Ranges:
TSH: 0.27 - 4.2 miU/L
FT4: 12.0 - 22.0 pmol/L
FT3: 3.1 - 6.8 pmol/L
Source: Reference Intervals for Children and Adults - Elecsys® Thyroid Tests’, Roche Diagnostics Limited, 2021).
Age-related reference ranges for children apply as displayed in the table below.
Please note there are also pregnancy related reference ranges displayed below.
| 0 -6 Days | 7-14 Days | 15 Days - 16 Years | |
|---|---|---|---|
| TSH (mIU/L) | 0.7 - 15.2 | 0.72 - 11.0 | 0.27 - 4.2 |
| Free T4 (pmol/L) | 11.0 - 32.0 | 11.5 - 28.3 | 12.0 - 22.0 |
| Free T3 (pmol/L) | 2.7 - 9.7 | 3.0 - 9.3 | 3.1 - 6.8 |
| 1st trimester | 2nd trimester | 3rd trimester | |
|---|---|---|---|
| TSH (mIU/L) | 0.3 - 4.6 | 0.4 - 4.1 | 0.2 - 3.2 |
| Free T4 (pmol/L) | 12.1 - 19.6 | 9.6 - 17.0 | 8.39 - 16.0 |
| Free T3 (pmol/L) | 3.8 - 6.0 | 3.2 - 5.5 | 3.1 - 5.0 |
Paediatric Ranges: Bristol Children's Hospital (adopted to harmonise ranges).
Pregnancy Ranges: Reference Intervals for Children and Adults - Elecsys® Thyroid Tests’, Roche Diagnostics Limited, 2021
To learn more about thyroid function testing visit Lab Tests Online or visit the British Thyroid Association website which includes links to various guidelines relating to the investigation and management of thyroid disorders.
Page Last Updated: 10/11/22
