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 (3,5,3',5'-tetraiodothyronine, LT4) monotherapy. 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. Since the 1970s, the synthetic prohormone,
levothyroxine (LT4), has been the most commonly prescribed
thyroid hormone in replacement monotherapy. It has been presumed that the peripheral conversion of T4 (3,5,3',5'-tetraiodothyronine) into T3 (3,5,3'-triiodothyronine) is sufficient to satisfy the overall tissue requirements. However, evidence is presented that this not the case for all patients, especially those exposed to indoor air molds. This retrospective study describes the successful treatment of nine patients in whom NTIS 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. 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.