Thyroid hormones subclinical hyperthyroidism

Subclinical hyperthyroidism is defined as a suppressed TSH level (below the normal range) in conjunction with normal thyroid hormone levels. Cardiac toxicity (eg, atrial fibrillation), especially in older persons, is of greatest concern. The consensus of thyroid experts concluded that hyperthyroidism treatment is appropriate in those with TSH less than 0.1 mlU/L, while close monitoring of the TSH level is appropriate for those with less TSH suppression. 

In the adult population, the prevalence of overt hypothyroidism is 19 per 1000 women and 1 per 1000 men with annual incidence of overt hypothyroidism is 4 per 1000 women and 0.6 per 1000 men. Subclinical hypothyroidism is also more common in women, the incidence increases with age, with up to 10% of women older than 60 years having an increased thyroid-stimulating hormone concentration. Subclinical hypothyroidism is more common in people who have been treated for hyperthyroidism with radioactive iodine or surgery, and in those with organ-specific autoimmune diseases, such as pernicious anaemia, type 1 diabetes mellitus, or Addison s disease. 

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