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Management of Subclinical Hypothyroidism - efficacy of Levothyroxine Treatment

المؤلف:  Wass, J. A. H., Arlt, W., & Semple, R. K. (Eds.).

المصدر:  Oxford Textbook of Endocrinology and Diabetes

الجزء والصفحة:  3rd edition , p560-561

2026-05-13

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The potential benefits of treating subclinical hypothyroidism include improvement in symptoms and quality of life, stopping progression to overt hypothyroidism and prevention of long- term complications. A previous systematic review of randomized controlled trials failed to demonstrate a benefit of levothyroxine treatment over placebo to improve symptoms or health- related quality of life in subclinical hypothyroidism. However, a subsequent randomized controlled trial found an improvement in tiredness with levothyroxine treatment. A recent randomized double- blind placebo- controlled trial of levothyroxine treatment in elderly patients (aged 65 years or above) failed to show an improvement in thyroid specific quality of life with the treatment in subclinical hypothyroidism. Furthermore, another randomized controlled trial in elderly patients (above the age of 65 years) found no benefit of levothyroxine in subclinical hypothyroidism to improve cognitive function.

There is some evidence to show improvement in lipid profile, features on echocardiography and cardiac magnetic resonance imaging, and arterial stiffness with levothyroxine replacement in subclinical hypothyroidism. However, at present, there are no large scale randomized controlled trials to show that levothyroxine treatment improves cardiovascular or cerebrovascular morbidity and mortality in subclinical hypothyroidism. Interestingly, a large observational study based on the UK general practice research database has found a reduction in fatal and non- fatal coronary heart disease events with levothyroxine in younger patients (aged between 40 and 70 years) with subclinical hypothyroidism, but not in older patients above the age of 70 years. In contrast, a large cohort study based on the Danish national registries showed no evidence of reduction in myocardial infarction, cardiovascular deaths, or all- cause mortality with levothyroxine treatment in patients with subclinical hypothyroidism, although all- cause mortality was reduced in patients under the age of 65 years.