Clinical Implications and Management of Sub Clinical Hyperthyroidism: A Review

Sub clinical hyperthyroidism (SCH) is characterized by normal free thyroid hormone concentrations along with a low or undetectable serum TSH (thyrotropin) level. The increased use of TSH as a screening measure and improved assay sensitivity is contributing to the diagnosis of sub clinical hyperthyroidism more frequently than ever in our clinical practise leading to the increased prevalence of the disease. The significance of SCH remains uncertain for most patients as some will revert to normal thyroid status over time whereas others will either remain static or progress to overt thyroid disease in the future. The detrimental effects of a persistently suppressed TSH has now been extensively studied and its effect on the cardiovascular system, the skeleton, mood disturbance, quality of life is quite significant leading to considerable morbidity and mortality. Majority of the patients are asymptomatic and lack overt features but the relevance of treatment is more focussed in elderly patients where the risk of developing cardiac arrhythmia and loss of bone mineral density is much more than young people in whom a conservative approach is usually preferred. The issue is contentious, the situation is challenging and the benefits of treatment are debatable. The consensus for who, when and how to treat is growing but still hasn’t been universally accepted. We attempt to review the recent literature available for sub clinical hyperthyroidism and suggest an analytical approach to its investigations and management.