Mortality was increased in untreated but not in treated hypothyroid individuals, independently of age and severity of hypothyroidism. Duration of decreased TSH in treated individuals had a greater impact on mortality than did duration of elevated TSH. These results stress the need for close monitoring of treatment in individuals receiving thyroid hormone replacement therapy.

No abstract

Mortality is increased in hyperthyroidism. Cumulative periods of decreased TSH increased mortality in both treated and untreated hyperthyroidism, implying that excess mortality may not be driven by lack of therapy, but rather inability to keep patients euthyroid. Meticulous follow-up during treatment to maintain biochemical euthyroidism may be warranted.