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HelpTest Code FT4 Free Thyroxine (FT4)
Additional Codes
| Epic Ordering Code | LAB127 |
| NBS code | LBC13351 |
| Service code | 31623 |
Specimen Requirements
Submit the following:
| Container: |
| Yellow Top |
Processing Requirements
Allow specimen to clot for 30 mins and centrifuge within 2 hours
Specimen type: Serum
Volume: 0.5mL
Specimen Stability
| Specimen Type | Serum |
|---|---|
| Ambient | 24 hours |
| Refrigerate | 6 days |
| Frozen | 1 month |
Specimen Condition
| Gross Haemolysis | Alert/Reject |
|---|---|
| Icterus | OK |
| Lipaemia | OK |
| Others | Not applicable |
Methodology
Chemiluminescent Immunoassay
Days and Times Performed
24 hrs, TAT 1 day
Reference Interval
| Age | |
|---|---|
| 0 – < 1 yr | 10.5 – 18.8 pmol/L |
| 1 yr – 18 yrs | 10.2 – 16.2 pmol/L |
| ≥ 19 yrs | 9.0 – 19.1 pmol/L |
Testing Laboratory
National University Hospital
Clinical Chemistry, 67724346
Useful For
Diagnosis of hyperthyroidism and hypothyroidism.
Update
Last updated 17/07/2026
LOINC Code Information
83121-4
Alias
Free T4 (Thyroxine)
Non-Protein Bound Tetraiodothyronine