Hormone Health Hub: Expert Insights on Testing, Balance & Better Living — T4 to T3 conversion

Thyroid symptoms can persist even when thyroxine (T4) levels appear normal — because thyroid function is profoundly affected by anything that disrupts the conversion of T4 to the active hormone T3 at the cellular level. In Part 1 of this two-part series, Margaret Groves of ZRT Laboratory explains the three deiodinase enzymes (D1, D2 and D3) that act as gatekeepers to intracellular thyroid hormone bioavailability, what affects circulating levels of T3 and reverse T3, and why selenium, iodine and inflammatory conditions all play a critical role.

Iodine deficiency is more common than many realise. This guide walks through how to assess iodine status using dietary recall, symptom profiling, and a three-part laboratory panel — including thyroid function, thyroglobulin, and urinary iodine and bromine testing.

The thyroid gland is under constant threat from modern life — oestrogen dominance, chronic stress, iodine and selenium deficiency, heavy metal toxicity and xenoestrogen exposure all suppress its function. This article outlines 7 key action steps you can take to protect your thyroid, from hormone rebalancing and stress reduction to targeted nutritional support and testing.

Millions of people struggle with weight gain, fatigue and low mood despite being told their thyroid test results are “normal.” The problem is that a standard TSH test alone cannot identify the full range of factors that suppress thyroid function — from oestrogen dominance and elevated cortisol to iodine deficiency, selenium deficiency, heavy metal toxicity and xenoestrogen burden. This article explains what those hidden saboteurs are and how targeted testing can help identify them.