From  1^st September  2014,  the  Clinical  Biochemistry  department  at Peterborough  City Hospital  will  implement  new  reference  ranges  for  thyroid function tests, namely TSH(thyroid stimulating hormone), FT4 (free thyroxine) and FT3 (free tri-iodothyronine). 

 

The changes are as follows:

 

Thyroid stimulating hormone (TSH):

 

Age/sex	Current reference range	Updated reference range
<12 months	1.36-8.80	0.7-11.0
1 – 6 years old	0.85-6.50	0.7-6.0
>6 years old	0.3-4.2	0.3-4.2
Pregnant 1st Trimester
Pregnant 2nd Trimester
Pregnant 3rd Trimester		0.2-3.2

 

 

 

Free thyroxine (FT4)

 

Age/sex	Current reference range	Updated reference range
All Ages	12-22	12-22
Pregnant 1st Trimester
Pregnant 2nd Trimester		9.6-17.0
Pregnant 3rd Trimester		8.4-15.6

 

Free tri-iodothyronine (FT3)

 

Age/sex	Current reference range	Updated reference range
<12 months	3.1-6.8	3.0-9.3
1 – 20 years old		3.9-8.0
>20 years old		3.1-6.8
Pregnant 1st Trimester
Pregnant 2nd Trimester
Pregnant 3rd Trimester		3.1-5.0

 

The changes are derived from data obtained from the departments supplier of the thyroid function test methods (Roche Diagnostics Ltd) and provide ranges tailored to patient age groups, and also trimester specific reference ranges in pregnancy  (as  recommended  in  the  ‘UK  Guidelines  for  the  use  of  Thyroid Function tests’ published by the Association for Clinical Biochemistry and the British Thyroid Association). 

 

If  you  have  any  queries  regarding  these  changes,  or  thyroid  function  tests, please contact the laboratory via email: peh-tr.chemimm@nhs.net [1]