Valued Westpac Lab Client and Care Provider,

NEW TSH normal ranges:

We would like to inform you that our TSH normal ranges are revised based on a 24,000 patient data set. Please find the new TSH normal ranges below. New TSH normal ranges are effective as of January 1, 2023.

TSH normal ranges
Sex Min Age Max Age Lower Range Upper Range
F/M 0D 4D 5.20 14.60
F/M 4D 31D 0.40 16.10
F/M 1M 24M 0.60 8.00
F/M 2Y 7Y 0.50 4.50
F/M 7Y 12Y 0.70 4.10
F/M 12Y 20Y 0.50 4.20 (prior 3.60)
F/M 20Y 115Y 0.40 4.40 (prior 4.10)

NEW Thyroid panel with TSH:

In addition, we have created a new Thyroid panel with TSH to assist with the evaluation of thyroid diseases. Test code E028 includes T3 uptake, Total T4, Free T4, and TSH.

The new test code is different from prior test code E446 by replacing Free Thyroxine Index by direct measurement of Free T4.

T4 circulates in the bloodstream as an equilibrium mixture of free and serum bound hormone. Free T4 (fT4) is the unbound and biologically active form, which represents only 0.03 % of the total T4. The remaining T4 is inactive and bound to serum proteins such as thyroxine binding globulin, TBG (75 %), pre-albumin (15 %), and albumin (10 %).

The determination of free T4 has the advantage of being independent of changes in the concentrations and binding properties of these binding proteins; additional determination of a binding parameter (T-uptake, TBG) is therefore unnecessary. Therefore free T4 is a useful tool in clinical routine diagnostics for the assessment of the thyroid status. It should be measured together with TSH if thyroid disorders are suspected and is also suitable for monitoring thyrosuppressive therapy.

If you have any questions, please reach out to Dr. Zoltan Nagymanyoki M.D, Ph.D., MBA, medical director via email at