OBJECTIVE: In a mortality follow-up of the HUNT Study, serum TSH within the 
reference range was positively associated with the risk of coronary death in 
women. We now aimed to confirm the association of high serum TSH with the risk 
of coronary heart disease, using hospital-based diagnoses of myocardial 
infarction.
DESIGN: Prospective population-based study with linkage to hospital information 
on myocardial infarction and to the national Cause of Death Registry.
PARTICIPANTS: A total of 26, 707 people without previously known thyroid or 
cardiovascular disease or diabetes at baseline.
MEASUREMENTS: Hazard ratios (HR) of coronary death and HRs of hospitalization 
with a first-time acute myocardial infarction, by baseline thyroid function.
RESULTS: During 12, years of follow-up, 960 (3·6%) participants had been 
hospitalized with first-time myocardial infarction and 558 (2·1%) had died from 
coronary heart disease. High TSH within the reference range was associated with 
increased risk of coronary death in women (P(trend) 0·005), but not in men. The 
risk of coronary death was also increased among women with subclinical 
hypothyroidism or subclinical hyperthyroidism, compared to women with TSH of 
0·50-1·4 mU/l. However, thyroid function was not associated with the risk of 
being hospitalized with myocardial infarction.
CONCLUSIONS: High serum TSH was associated with increased mortality from 
coronary heart disease in women, but we found no association of thyroid function 
with the risk of being hospitalized with myocardial infarction. Thus, the 
morbidity finding does not confirm the suggestion that low thyroid function 
within the clinically normal range is associated with increased risk of coronary 
heart disease.