Selenium deficiency in mineral-rich mid-Western Australia.
Selenium is an essential micronutrient for human beings. Selenoproteins play a role in anti-oxidation and in maintaining immunity. Selenoproteins are distributed in all tissues, the most important of which are glutathione peroxidase, thioredoxin reductase and deiodinases. The deiodinases are selenium-dependent enzymes. An elderly man with lethargy and tiredness who had normal free thyroid hormone T4, thyroid-stimulating hormone and a low T3 with subnormal temperature and low selenium level. Selenium supplementation normalised thyroid function tests. Physicians should have high level of suspicion to identify selenium deficiency as an effective replacement will cure the causative disorder.