Free thyroxine (fT4)

Test/Investigation

Free thyroxine (fT4)

Site(s) or Laboratory offering Test/Investigation

NNUH, QEH, JPUH

Units

pmol/L

Comments/Precautions

Part of thyroid profile for the investigation of thyroid disorders. Please contact the lab if you suspect assay interference

Sample type

Serum

Turnaround times (TAT) Urgent/Routine/GP or OPD

1 hour / 4 hour / by 8am next day

Reference intervals (adult unless stated)

Adult (> 18 yr) range: 9.0 – 19.1 pmol/L

Paediatric ranges:
5 days – 14 days 13.5 – 41.3 pmol/L
15 days – 29 days 8.7 – 32.5 pmol/L
30 days – < 1 yr 11.4 – 21.9 pmol/L
1 yr – < 19 yr 9.3 – 17.6 pmol/L (n=952)

If UKAS Accredited Test indicate at which site

Y NNUH