SCH - indicated by a raised thyroid-stimulating hormone but normal thyroxine level is detectable only through blood tests.
With the help of Preventive Cardiology Information System, the team from the Cleveland Clinic studied more than 6,000 patients
They evaluated TSH at each patient's initial visit and linked with demographic and laboratory data. Mortality was measured six years later and survival was compared amongst subjects with varying levels of TSH.
They found that patients with either hypothyroidism or moderate SCH were at increased risk of dying than patients with normal thyroid function.
Previous studies have shown that hypothyroidism increases risk for cardiovascular disease and mortality, data to date regarding the relationship between SCH and mortality and cardiovascular disease is inconclusive.
"These data demonstrate that the previously reported correlation between hypothyroidism and cardiovascular disease and mortality is extended to a population who is at high risk for cardiovascular disease, but whose cardiovascular risk factors are also pretty aggressively treated," said Dr. Mario Skugor, principle investigator of the study.
"The data also demonstrate that patients with moderate SCH are at increased risk of death and poor cardiovascular health. These findings suggest that patients with moderate SCH should be treated with L-thyroxine therapy as this treatment may reduce mortality," he added.
The study was presented at the 79th Annual Meeting of the American Thyroid Association in Chicago, Ill.