Approach to the Patient With a Suppressed TSH

Abstract

Subclinical hyperthyroidism is a laboratory diagnosis defined by a serum thyroid stimulating hormone (TSH) concentration below the reference range (< 0.4 mU/L in most assays), and a free thyroxine (FT4) and triiodothyronine levels (FT3) in the reference range. Many patients diagnosed with subclinical hyperthyroidism will be clinically euthyroid while others may present with manifestations characteristic of thyroid hormone excess, such as tachycardia, tremor, intolerance to heat, bone density loss, or weight loss. In addition to the laboratory abnormalities, patient factors such as age, symptoms, underlying heart and bone disease, are used to stratify patients for the risk of adverse outcomes and determine the appropriate treatment. Evaluation should include repeat thyroid function tests to document persistent TSH suppression, investigation of the underlying cause, as well as evaluation of the patient’s risk of adverse outcomes in the setting of a subnormal TSH. Persistent subclinical hyperthyroidism has been associated with an increased risk of a range of adverse events, including, cardiovascular events such as atrial fibrillation and heart failure, bone loss and fracture, and in some studies, cognitive decline. Despite the consistent association of these adverse events with subclinical hyperthyroidism, prospective studies showing improved outcomes with treatment remain limited. Management options include observation without active therapy, radioactive iodine ablation of the thyroid, antithyroid medication, thyroid surgery, or radiofrequency ablation, as appropriate for the patient and clinical setting. The choice of therapy should be guided by the underlying etiology of disease, patient factors, and the risks and benefits of each treatment option. (248 words)

Thyroid dysfunction in the ageing patient

“…There is wide agreement in treating persistently TSH levels < 0.1 mU/L in subjects ≥ 65 years [55], since a greater risk of hyperthyroidism-related complications and progression to overt hyperthyroidism have been reported in subjects with TSH levels < 0.1 mU/L compared to those with persistent TSH levels between 0.1 and 0.4 mU/L. There is less evidence supporting the treatment of subclinical hyperthyroidism in subjects with persistent TSH levels between 0.1 and 0.4 mU/L [56]. Some studies have revealed that even mild subclinical hypothyroidism could entail a higher risk of adverse outcomes in older patients, including cardiovascular disease, bone fragility and overall mortality; treatment for mild subclinical hyperthyroidism should also be considered in this population [57].…”