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Why would I need a Thyroid Test?

Updated: Jan 12, 2023

Eww, that word--test. It suggests a pass or a fail. It's probably best to substitute 'check' for 'test.'

A thyroid 'check' can be beneficial.

What does a thyroid do?

It monitors and regulates many functions such as digestion, energy, temperature regulation, weight, heart and muscle function. So yeah, it's pretty important. It acts a bit like the accelerator of a car. It decides how fast or slow metabolism will be and through complex feedback pathways manages to keep things on an even keel. Most of the time!

The thyroid runs on various hormones, vitamins and minerals. Maybe you've heard of T3, T4, free or not, TSH and the like. The conversion of T4 (thyroxine) to the active thyroid hormone, T3 (triiodothyronine) involves the cleaving an iodide. T4 has four iodides and T3 has, you guessed it, three iodides. This process requires zinc and selenium and occurs in the thyroid, liver, intestinal tract and kidneys. When all of these are at a level of optimal health chances so is the thyroid.

Vitamin A can be prescribed with low thyroid as it is shown that beta-carotene (prohormone of Vitamin A) has a lower conversion rate in hypothyroidism. Whether it is a genetic predisposition or a lack of cofactors such as zinc, selenium and vitamin C remains under study.

B vitamins are imperative for thyroid health and hormone manufacture. If there is a genetic condition where activated B vitamins are required, supplementation with them can provide support. Usually, but not always, a high level of homocysteine suggests the MTHFR gene expression.

And iodine, of course. Supplementation is delicate and more is not necessarily better. Foods that are rich in iodine are seaweed, oysters, cod, lima beans, prunes, green peas, eggs and liver. New Zealand soils are notoriously low in essential minerals. Thank goodness for the sea!

There is a lesser known hormone, thyrotropin-releasing hormone, found in the hypothalamus (part of the brain.) Its release stimulates the thyrotropin cells in the anterior pituitary gland to release the well known TSH (thyroid stimulating hormone.) There is a complex loop of feedback systems that ensures appropriate function and release of TSH. The HPA (Hypothalamus, Pituitary, Adrenal) axis which helps regulate stress response, bodily functions and hormone levels. Stressful events or prolonged stress can disrupt the delicate feedback mechanisms creating disease, hormonal irregularities, increased cortisol levels, digestive problems, autoimmune conditions, thyroid conditions, and more.

When there is a diagnosis of thyroid problems, it is a multifactorial consideration as to why it's happened and how to treat.

What disrupts thyroid function? Stress. Glorious stress. HPA axis disruption.

MTHFR, a need for activated B vitamin supplements due to this genetic condition. Disrupted gut biome.

Poor diet, Food intolerances.

Heavy metals, Glyphosate, Environmental Toxins, Mould.

Mineral deficiencies. Low vitamin D.

Gall bladder removal/Gallstones (an indication of low thyroid function)

Autoimmune disease.

Liver disease. Kidney disease.


Have you been told any of these? You're healthy, you're getting through your day.

Maybe you're just a bit tired.

Your hands are shaky, big night out last night?

Why are you so cranky?

What's wrong with you?

Get some sleep.

Eat better.

Exercise will help.

You're young.

You worry too much.

It is so very common to hear, unfortunately.

And remember, just because there's fatigue it does not automatically mean a low thyroid. With an overactive thyroid there is exhaustion, too. Sad, eh? Think of all that could be accomplished if the thyroid worked overdrive. It's quite the opposite. They are usually told it's chronic fatigue without the markers.

The Nerd has copied some information from FxMed in New Zealand with respect to hyperthyroidisim (over active--not overachieving) and hypothyroidism (underactive--not to be confused with underachieving!)


  • Depression

  • Dry skin and brittle nails, or hair loss

  • Feeling tired or weak

  • Increased sensitivity to cold

  • Heavy or irregular menstrual cycles

  • Obesity

  • Joint Pain

  • Infertility

  • Constipation

  • Memory issues or unclear thinking

  • Hashimoto’s

  • Outer third of eyebrows are thin or missing


  • Nervous or moody

  • Shaky hands, fast heartbeat

  • Sensation of being hot and sweaty

  • Increased bowel movements

  • Fine, thin hair, and hair loss

  • Weight loss without a change in eating patterns

  • Difficulty concentrating

  • Sleep problems or restlessness

  • Goiter or thyroid nodules

  • Weak, tired, fatigued

Many times the hard working thyroid is overlooked.

'My tests came back normal.'

'I'm taking iodine.'

'I just need more sleep.'

In New Zealand the 'normal' range for TSH is 0.4 - 4.0 mIU/L.

If the test is 0.6 mIU/l it's 'low' but within normal range.

In the herbal world that number suggests TSH is too low.

We want you somewhere in the middle. We need to look at possible reasons why.

We want more information from blood work.

Ideally the test is combined with other markers, such as T3, FT3 & T4, FT4, to see if thyroxine (T4) and triiodothyronine (T3) are being utilised within range. Throw in a thyroid antibodies test and thyroglobulin indicator and we're away to the races. Thyroglobulin is a prohormone (a precursor) made by the thyroid and used in thyroid hormone manufacturing. Its levels can be an indication of thyroid health but a test for thyroglobulin antibodies can show if the immune system is attacking the thyroid.

Some additional tests to consider: CRP--Inflammation eGFR--Kidney function.

LFT--Liver function test or at least CGT & ALP.

FBC with film--Immune health, Parasites, Macrocytic anaemia.

More from FxMed. They have a thyroid testing kit:

The Complete Thyroid Profile Measures the following from a single blood draw:

  • Thyroid Stimulating Hormone (TSH) – TSH causes the thyroid gland to make two hormones, T3 and T4, which help control the body’s metabolism. This test is done to find out whether the thyroid gland and brain-thyroid communication are working properly.

  • T4, Total – This test measures the total amount of T4 (Thyroxine) in blood.

  • T4, Free – Most of the T4 in the body binds to protein, the T4 that does not is called ‘free T4’ and circulates unbound in blood. This test measures the free T4 level individually also.

  • T3, Total – T3 (triiodothyronine) is the most important thyroid hormone for the body’s control of metabolism. This test measures the total amount of T3 in blood.

  • T3, Free – Most of the T3 in the body binds to protein, the T3 that does not is called ‘free T3’ and circulates unbound in blood. This test measures the free level individually also.

  • T3, Reverse – Reverse T3 is converted by the liver from the stored hormone T4, it is the body’s main way of getting rid of unneeded T4 every day. Sometimes the body can make too much reverse T3 from a number of causes including chronic emotional, physical, or biological stress, chronic sickness, after surgery, diabetes, ageing, or an acute injury. This test measures for levels of reverse T3.

  • Thyroid Peroxidase (TPO) Antibody – Thyroid peroxidase (TPO) is an important enzyme for producing thyroid hormone. TPO converts T4 to T3. High levels of TPO antibodies suggest the immune system is mistakenly attacking this enzyme and the thyroid gland, compromising thyroid activity.

  • Thyroglobulin (Tg) Antibody – Thyroglobulin (Tg) is a protein produced and used by the thyroid gland to make the hormones T3 and T4. High levels of antibodies to Tg suggest the immune system is mistakenly attacking the thyroid gland.

Currently the price of the test is $145 NZD.

The Nerd is happy to provide the kit for you. You are emailed a copy of your results which you can take to your healthcare provider of choice or chat with The Nerd about the next step. Or you can get a test through Labtests New Zealand for TSH, FT3, FT4 for $48.00!

But what about herbal stuff for the thyroid? Where's that information?? You'd think being a herbalist and all that there would be something of that nature here. Well, it is a subject that can go on for pages and pages. One on herbal support for the thyroid in the future is a definite requirement!

But for now, hopefully you've found this brief outline helpful and informative.



A herbal nerd of sorts.

Information courtesy of:

A video explaining thyroid function and test results.


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