Subclinical Hypothyroidism in Adults- to Treat or Not?

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Background: Subclinical hypothyroidism (ScHt) is a condition in which the Laboratory reports show normal T3 or FT3, normal T4 or FT4, and increased TSH concentrations, associated with few or no signs & symptoms of hypothyroidism. ScHt prevalence is estimated to be ranging from 4% to 20% of adults, with a higher prevalence in women, older people, and those with thyroid autoimmunity. It is higher in iodine-sufficient areas and genetics also plays a role. ScHt can progress to overt hypothyroidism, especially if antithyroid antibodies are present. It has been associated with adverse metabolic parameters like dyslipidaemia, reproductive, maternal-foetal, cardiovascular, neuromuscular, and cognitive abnormalities. ScHt among pregnant women is significant as the prevalence of overt & ScHt among them is reported to be 2.5 % and almost fourfold (9.54%) respectively. The good news is that half of the cases resolve spontaneously in within 2 years. Methods & Materials: This article is an outcome of literature review following the author and his son’s annual blood test results showing indications of ScHt in late February 2024. Results: The results of annual blood tests in a recognised laboratory showed TSH levels of 6.233 and 7.529 respectively for the author and his son respectively. The authors Hb1Ac were 6.4 despite being just on oral anti-diabetics (with diet control and exercise routine) since 1991, indicative of a good management. It was surprising to note that both have ScHt. However, after an intensive literature search and discussions decided for “a wait and watch strategy” instead for jumping for treatment. Conclusion: In India 4% to 20% of adults have subclinical hypothyroidism, with a higher prevalence in women, older people, and those with thyroid autoimmunity. Though ScHt can progress to overt hypothyroidism, especially if antithyroid antibodies are present, half of the cases are expected resolve spontaneously in within 2 years. As most endocrinologists, Cardiologists and Public health professionals in India do not recommend treatment for 1-2 year unless either i) when TSH >10 mIU/L, or signs become explicit, or ii) Cardiovascular risk individuals, we have decided to monitor the progress for entire 2024 with quarterly assessments of the parameters.