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Test Directory -  Thyroid Function Tests



Clinical Indications

Screening for suspected thyroid disease and monitoring treatment for hypo- and hyperthyroidism. Guidelines on thyroid function testing are available.

Test Includes

TSH is measured as a first line test followed up with free T4, free T3 and thyroid antibodies as indicated - see laboratory TFT strategy. . 

Request Form 

Combined Pathology Blood form (Yellow/Black or Blue for GP's). 
In order to help with provision of clinical details and selection of appropriate tests, request forms include several tick boxes for thyroid function:


TFT1 - Thyroid Disease?



TFT2- On Thyroxine



TFT3 - Anti-Thyroid Rx



On request.

Specific Criteria

None. It is normally not necessary to repeat TFT's within 4 weeks. Repeat TFT requests within 14 days will be blocked unless requested by Consultant Endocrinologist team.

Patient Preparation



This 'TSH first' strategy can give a false indication of thyroid status in pituitary dysfunction. Therefore, requests for thyroid function where pituitary dysfunction is known or suspected, must be clearly indicated so that appropriate tests can be undertaken.

Turnaround Time

Same day




0.5 ml


Yellow top (SST) tube or

Paediatric orange top (lithium-heparin)

Causes for Rejection

Unlabelled sample

Reference Range

See individual tests TSH, free T4, free T3


Interpretive comment will be provided based on clinical information and the results.

Lab Handling

Processing: Analysed from primary tube and stored at 4C in the cold room (CB23)


Version 1.1 / March 2015                                                                                                        Approved by: Consultant Biochemist