With around 15% of the UK population suffering from Thyroid related issues, you might have noticed an upsurge in the number of your clients appearing to suffer from thyroid disorders, or symptoms that suggest an underlying thyroid issue. If you’re having trouble pinpointing whether your client may have thyroid issues, some of the symptoms that could indicate a need for further investigation include fatigue, constipation, weight gain and low mood. If you want to better support clients with suspected or confirmed thyroid dysfunction, read on.

“My client is telling me they’ve had their thyroid tested by their GP”

It is commonplace that many clients with the symptoms listed above are likely to have been given an all clear on the thyroid front from their GP, and so may be sceptical if you suggest further exploration of this through blood chemistry analysis. It’s important for your client to understand that, generally, GPs are only able to request screening for top level thyroid hormones and that there are a wide range of markers that enable a full picture which are only available through functional testing.

How best to approach the thyroid condition from a functional perspective

In order to help clients get to the root of their symptoms, we need to keep in mind that the thyroid (just like any other organ in the body) does not exist and function in a vacuum; so looking at it in isolation will only give us a very limited part of the picture.

A complete thyroid panel will include the following markers:

  • TSH
  • Total T4
  • FreeT4
  • TotalT3
  • FreeT3
  • Reverse T3
  • T3 Uptake
  • Thyroid peroxidase antibodies
  • Thyroglobulin antibodies
  • TSH receptor antibodies
  • rT3 and Free T3 to T4 ratios
  • Parathyroid hormone
  • Thyroid binding globulin
  • Free Thyroxine Index (T7)

This is a comprehensive list of markers, which can give a view on general thyroid function: whether it’s under-producing or over-producing thyroid hormones. However, even this comprehensive range of markers has some gaps. What these markers cannot tell us is far more important:

  • Why – is there a conversion issue? What might be influencing antibodies? What might be driving rT3?
  • What – other crucial systems are being affected by the suboptimal thyroid function?

Taking a whole-body approach, some of the systems affected by thyroid dysfunction or associated with thyroid dysfunction include:


Thyroid hormones enhance expression of LDL receptors, so if low this can contribute to hypercholesterolemia.


Thyroxine has a pro-relaxing effect on the Sphincter of Oddi which expresses thyroid hormone receptors – there is an association between low thyroid function and low bile flow. Low thyroid function can promote synthesis of cholesterol, increasing risk of gallstones

Liver Enzymes

Hyperthyroidism is associated with increased ALT and ALP. Hypothyroidism is associated with increased AST.

Glucose metabolism

Thyroid hormones enhance insulin-dependent glucose entry into the cells. Both hyperthyroidism and hypothyroidism have been associated with insulin resistance via different mechanisms. Combined HbA1c and TSH levels that are high normal (so suboptimal), are associated with a higher risk of coronary heart disease.


Low thyroid function has been correlated with shifts in electrolyte patterns, such as increased phosphorous and calcium, and decreased sodium and potassium.

Nutrient status

Hyperthyroidism can negatively affect nutrient absorption, especially fats.

Immune function

White blood cell chemotaxis, phagocytosis, and cytokine synthesis can be altered in hypo or hyperthyroidism.

Sex hormone function

Low thyroid function associated with low oestrogen and testosterone levels in women.  Thyroid hormones indirectly increase SHBG. Hyperthyroidism is linked to higher LH, SHBG and Oestrogen. Hypothyroidism can affect release of GnRH required for LH, FSH and subsequent ovarian release of oestrogen and progesterone

System biomarkers that are invaluable in the interpretation of thyroid function are:

Inflammatory markers

Associated with increase in rT3. Can cause under-conversion. Can be related to autoimmunity.

Infection and pathogen markers

Can be trigger or driver for autoimmunity. Primary thyroiditis can be viral in nature. If chronic this can lead to under-conversion.

Heavy metal markers

Can be trigger or driver for autoimmunity. Can contribute to rise in rT3.

Oxidative stress markers

Can cause under-conversion. Can cause rise in rT3.

Nutrient status

Low iodine can be cause of primary hypothyroidism. Zinc and Selenium depletion can cause T4>T3 under-conversion. Vitamin D plays a role in autoimmunity, so relevant if thyroid antibodies are raised. Iron, protein status and other micronutrients can all affect thyroid function and their depletion is associated with poor thyroid function.

Methylation markers

B6, B12, folate, homocysteine, creatinine can all provide preliminary information on someone’s methylation activity which is relevant to autoimmunity and detoxification both of which can be relevant to dysfunctional thyroid.

Bile markers

Reduced bile flow can contribute to under-conversion, as the DIO2 enzyme is bile dependent as well as selenium dependent.

Liver function markers

Much of the T4 to T3 conversion takes place in the liver so dysfunctional liver can lead to under-conversion. Liver disease such as cirrhosis is associated with low T3 and high rT3. Liver diseases can be associated with high thyroxine and thyroxine binding globulin.

Gut permeability markers

Relevant in the case of autoimmune thyroiditis.

Adrenal stress markers

High cortisol can cause under-conversion.

Sex hormone function

Oestrogen increases Thyroxine binding globulin and the need for thyroid hormone in women with hypothyroidism.

The best way to support your clients with suspected thyroid dysfunction

Understanding how all associated systems are being affected as well as how other body systems may be driving the thyroid imbalance is crucial to supporting your clients in reclaiming their vitality. All of the system biomarkers outlined above as essential for getting the most out of functional testing when it comes to thyroid dysfunctional clients are included in the FDX thyroid panel. You can get the complete picture and support your clients with true health transformation by taking a full systems approach, using FDX blood chemistry analysis.