Specimen Collection

Sample stability:

• 8 days at 20-25 ^o C
• 14 days at 2-8 ^o C
• 24 months at -20 ^o C

4.5 mL PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

4 mL EDTA Blood

5 mL Heparin Blood

4 mL Plain Blood

3.5 mL Adult SST Blood

0.5 mL Paediatric Microsample Blood

0.5 mL Paediatric Micro-heparin Blood

0.5 mL Paediatric Micro-EDTA Blood
Reference Intervals

Units: mU/L

Reference ranges:

4 days - 1 month	0.4 - 16.0
1 month - 1 year	0.6 - 8.0
>1 year - 18 years	0.5 - 4.5
>18 years	0.27 - 4.2

Pregnancy:

Gestational age (weeks)	TSH (mU/L)
<7 (as non-pregnant)	0.3 - 4.2
7 +0 - 13 +6	0.1 - 3.5
14 +0 - 28 +0	0.2 - 3.8
28 +1 - 40 +0	0.3 - 3.8

Uncertainty of Measurement: 10% below level of 0.050

5% at levels of 5 mU/L and higher

Turnaround Time: Within 3 hours
Assay Method

Principle: Sandwich type immunoassay with chemiluminescence detection

Reagents: Roche TSH kit

Analyser: Cobas e801

Diagnostic Use and Interpretation

Increased in primary hypothyroidism.

Decreased in hyperthyroidism.

In secondary hypothyroidism due to pituitary disorders, it may "normal" or low, with a low free T4 .

Temporary hypothalamic/pituitary dysfunction (aka 'sick euthyroid syndrome') may occur with acute illness and can create a confusing thyroid function pattern. Therefore, it is generally NOT recommended to assess thyroid function when a patient is acutely unwell, unless it is believe that thyroid dysfunction is the basis of the illness.

Reference:

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

Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

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: Sakunthala@adhb.govt.nz ext. 23427

Last updated at 14:37:55 08/04/2025