Thyroid testing is something I recommend to a lot of my weight loss clients, and that’s because if your thyroid isn’t working properly, weight loss can be really difficult!  Your thyroid regulates your metabolism, so it’s important to have a healthy thyroid in order to lose weight.

When you get your thyroid levels checked through your GP, there are a number of tests that might be ordered depending on your doctor.  I always tell my clients this: there is a BIG difference between “normal” blood test results and “optimal” blood test results, and this is especially true when it comes to your thyroid.

Normal results mean you don’t have a disease (or at least, not based on what was tested).  Optimal means your thyroid is working at it’s most ideal, which is what we want to see. If your thyroid levels are “normal” but you still can’t lose weight, and you have all the symptoms of hypothyroidism *link: 5 symptoms of an underactive thyroid then your results might not be optimal.  And optimal thyroid health is what we want, especially for weight loss!

First things first, what should you get tested to find out what is going on with your thyroid?

Basically: as much as you can.

A lot of doctors in Australia (I don’t know about other countries) will only test TSH (thyroid stimulating hormone) to assess thyroid function.  And unfortunately, TSH has proven to be quite an inaccurate indicator of thyroid health. It’s not even produced by the thyroid – it comes from a different gland!  So if you want to get your thyroid checked, make sure you at least get these three hormones tested:

  • TSH
  • T3
  • T4

T3 and T4 are two important thyroid hormones, and assessing the levels of each of them, alongside TSH, will give you a much better indication as to what your thyroid is actually doing.  Assessing ratios between T3 and T4 can also highlight possible nutritional deficiencies (like iodine and selenium) that might be impacting your thyroid health.  Which are super important to know!

If possible, get your reverse T3 tested as well (rT3).  This hormone will tell you whether or not you have an issue in converting T4 to T3.  Thyroid auto-antibodies are also recommended.

How to understand your thyroid test results

So what levels are normal, and what levels are ideal?

Based on independent research, the table below highlights the differences between normal and optimal ranges when it comes to thyroid levels.  This is based on Australian levels and may vary for other countries.

Thyroid hormone

Normal range

Ideal range


0.3-5 mU/L

1-2 mU/L


2.6-6 pmol/L

4-5 pmol/L


9-19 pmol/L

14-19 pmol/L


140-540 pmol/L

Less than 240 pmol/L

The above ranges are taken from Clinical Naturopathy by J. Sarris & J. Wardle.  Please consult your health care practitioner if you have any questions about testing and reference ranges.

If you suspect you have an underactive thyroid, I highly recommend working with a practitioner who will test your levels thoroughly, and work from the ideal ranges to give you the very best chance at successful, long-term weight loss.

Ready to get your thyroid sorted?

The most comprehensive package I have is the Thyroid Health Program, which includes complete, comprehensive testing for thyroid hormones, as well as other essential markers that can impact your thyroid function.  For information on the program and how to work with me, click here.