Specimen Collection

Sample stability:

• 5 days at 20-25 ^o C
• 7 days at 2-8 ^o C
• 30 days at -20 ^o C

4.5 mL PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

5 mL Heparin Blood

4 mL Plain Blood

3.5 mL SST Blood

0.5 mL Paediatric Microsample Blood

0.5 mL Paediatric Micro-heparin Blood
Reference Intervals

Units: pmol/L

>=4 days - 7 years	3 - 10
>7 years - 19 years	3.5 - 8.0
>19 years - Adult	3.9 - 6.8

Pregnancy:

1st trimester	3.8 - 6.0
2nd trimester	3.2 - 5.5
3rd trimester	3.1 - 5.0

The reference interval is highly variable during the first three days of life.

Please contact a Paediatric Endocrinologist or Paediatrician if interpretation of these results is required.

Uncertainty of Measurement: 0.4 pmol/L for results around 3.0 pmol/L

6% for results around 9.0 pmol/L

Turnaround Time: Within 3 hours
Assay Method

Principle: Competitive type immunoassay with chemiluminescence detection

Reagents: Roche e-pack FT3-3

Analyser: Cobas e801

Diagnostic Use and Interpretation

Increased in hyperthyroidism.

Decreased in hypothyroidism.

See Thyroid Function Tests

Reference:

Roche Diagnostics: Thyroid function test Reference Intervals for Children and Adults

Contact Information

The chemical pathology team can be reached via email: chemicalpathologist@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000 or 09-3078995

Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.

After-hours: contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours .

• Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
• Dr Cam Kyle : CampbellK@adhb.govt.nz ext 22052
• Dr Weldon Chiu : WeldonC@adhb.govt.nz ext. 23427
• Dr Campbell Heron : CHeron@adhb.govt.nz ext. 23427
• Dr Sakunthala Jayasinghe Saku.Jayasinghe@adhb.govt.nz
• Dr Owen Yi WenyiYi@adhb.govt.nz

Last updated at 11:42:03 16/01/2026