Free T4 | KK Women's and Children's Hospital

Specimen Container	Gel separator tube (Adult) Microtube (Paeds)
Specimen Requirement	Plain Blood Adult: 5 mL Paediatric: 1.3 mL Invert blood 5 times after blood collection ensures the clot activator is well mixed with the blood. This will ensure results are reliable.
Orderable as Urgent?	Yes
Turn Around Time	3 - 4 hrs
Reference Value(s)	- Cord: 12.5-27.5 pmol/L - <3rd day: 25.7 -64.3 pmol/L - 3rd-30th day: 11.6 to 28.3 pmol/L - 31st day-18th year: 10.3-25.7 pmol/L - Adult: 9.0 - 19.1 pmol/L Free T4 reference intervals for women with singleton pregnancies 15-50 years old (inclusive) 09 to 14 wks gestation: 11.4 - 19.5 pmol/L 18 to 22 wks gestation: 10.1 - 15.4 pmol/L 28 to 32 wks gestation: 9.5 - 14.9 pmol/L 34 to 39 wks gestation: 8.9 - 14.7 pmol/L
Testing Laboratory Location	KKH
Laboratory	Clinical Chemistry
Contact Number	6394 1383
Day and Time Performed	Mon - Fri: 0800 hrs to 1700 hrs Sat: 0800 hrs - 1230 hrs
Orderable on CPOE?	Yes
Downtime Form	Clinical Chemistry - Form A
Additional Information	Critical Value: below 2 months old only < 5.2 pmol/L

Change History Notes

16 Nov 2021 10:00 AM

Updated Specimen Requirement, Reference Value(s) and Additional information.

Last Updated - 05 Apr 2025