Can mould cause thyroid issues?

Welcome to my blog post ‘Can mould cause thyroid issues?’. This blog assumes you are up to speed with what mycotoxins are, the signs and symptoms of mycotoxin illness, and how to test for them. If not, you may also be interested in the section of my blog dedicated to mycotoxins, click here, in particular:

• Mycotoxin Testing What You Need To Know
• Can Mould And Mycotoxins Cause Chronic Fatigue Syndrome?
• Can Mould And Mycotoxins Cause Gut Problems Such As IBS?

Exposure to volatile organic compounds including metabolites produced by toxigenic fungi, some of which are inflammatory agents, can lead to a deficiency or imbalance of many hormones, such as insufficient amounts of the active form of thyroid hormone, commonly abbreviated to T3 hormone

Can mould cause thyroid issues?

Long-term exposure to dampness microbiota induces multi-organ morbidity. One of the symptoms related to this disorder is non-thyroidal illness syndrome (NTIS). A retrospective study was carried out in nine patients with a history of mold exposure, experiencing chronic fatigue, cognitive disorder, and different kinds of hypothyroid symptoms despite provision of levothyroxine monotherapy (1).

Exposure to volatile organic compounds present in water-damaged buildings including metabolic products of toxigenic fungi and mold-derived inflammatory agents can lead to a deficiency or imbalance of many hormones, such as active T3 hormone (1).

A retrospective study (1), the inspiration for this blog post, describes the successful treatment of nine patients in whom non-thyroid illness syndrome was treated with T3-based thyroid hormone. The treatment was based on careful interview, clinical monitoring, and laboratory analysis of serum free T3 (FT3), reverse T3 (rT3) and thyroid-stimulating hormone, free T4, cortisol, and dehydroepiandrosterone (DHEA) values. The ratio of FT3/rT3 was calculated. In addition, some patients received adrenal support with hydrocortisone and DHEA. All patients received nutritional supplementation and dietary instructions (1).

During the therapy, all nine patients reported improvements in all of the symptom groups. Those who had residual symptoms during T3-based therapy remained exposed to indoor air molds in their work places. Four patients were unable to work and had been on disability leave for a long time during LT4 monotherapy. However, during the T3-based and supportive therapy, all patients returned to work in so-called “healthy” buildings.

The importance of avoiding mycotoxin exposure via the diet is underlined as DIO2 genetic polymorphism and dysfunction of DIO2 play an important role in the development of symptoms that can be treated successfully with T3 therapy (1).

How Do Mycotoxins Cause Thyroid Issues?

Thyroid hormones play a very important role in development, growth, and glucose–fat–protein metabolic homeostasis in all tissues by affecting the expression of many genes. It has been shown that the most important factors in thyroid hormone regulation are the activities of the three deiodinase enzymes (DIO 1, 2, 3).

In particular, DIO2 regulates the activities of thyroid hormone action by metabolizing the precursor molecule thyroxine (T4) that is secreted by the thyroid gland into the biologically active molecule, T3. Two of the deiodinases (DIO1, DIO2) contain selenium and are responsible for transforming T4 either into its active metabolite, i.e., T3 or to an inhibitory reversed T3 form, rT3 (DIO3) (1).

The importance of DIO enzymes in thyroid hormone homeostasis has become increasingly clear by experiments conducted in DIO knockout mice. DIO enzymes affect the thyroid hormone regulation by controlling thyroid hormone homeostasis at the cellular level, such as in the case of symptoms in mould exposure or in other situations in which there is a lack of active T3 hormone in the peripheral tissues or brain.

A deficiency of active cellular T3 hormone has been described as a non-thyroidal illness syndrome (NTIS).

The patients with this disease presents with normal function of thyroid or with required exogenous T4 with normal thyroid-stimulating hormone (TSH), free T4 (FT4), and free T3 (FT3) values in the blood, but still with symptoms of hypothyroidism. Importantly, the major part of T3 is generated locally from T4 by DIO2 in most tissues of the body and in the brain, especially at the hypothalamus–pituitary level (1).

The toxins released by the microbes living in damp buildings can induce oxidative stress (OS).

Oxidative stress has been proposed to be one of the most important mechanisms behind the adverse health outcomes associated with living in a damp indoor environment. One of the putative consequences of mycotoxin-induced OS is a blockade of crucial mitochondrial functions.

Oxidative stress may cause inflammatory responses by increasing the production of reactive oxygen species (1).

Oxidative stress also impacts negatively on various hormonal influences, e.g., causing antioxidant imbalance and impairing the functions of the deiodinase enzymes. For example, oxidative stress reduces the capacity of DIO2 to convert thyroxine (T4) into its biologically active form of T3.

Thus, oxidative stress can be defined as a failure of the antioxidant system to cope with the excess of free radicals.

One putative hypothesis is that oxidative stress facilitates the development of hypothyroidism or rather a lack of availability of the T3 hormone at the tissue level, the so-called non-thyroid illness syndrome.

Patients who have been exposed for a prolonged time to indoor air molds have high serum levels of rT3 (1) (unpublished observation from the authors of the paper).

This indicates an imbalance between rT3 and FT3 and decreased tissue metabolism of T4 to be converted to T3, in other words non-thyroid illness syndrome. In these patients, DIO2 does not function properly, therefore T3 therapy is indicated.

The rationale for T3 therapy is: T3 is biologically active hormone that does not require activity of the DIO2 which is needed for conversion from endogenous prohormone T4 to active T3 hormone, or when exogenous levothyroxine (LT4) monotherapy is administered (1).

Summary For ‘Can mould and mycotoxins cause thyroid issues?’:

• This article describes the successful treatment of patients with hypothyroidism and non-thyroid illness syndrome.
• The disease developed after prolonged and cumulative or massive exposure to indoor air dampness microbiota.
• A combination of nutritional therapy, suppleemnts and T3 therapy were needed.

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References For ‘Can mould and mycotoxins cause thyroid issues???’:

1. Non-Thyroidal Illness Syndrome in Patients Exposed to Indoor Air Dampness Microbiota Treated Successfully with Triiodothyronine: click here.