Endocrine Abstracts

Introduction: Subclinical hypothyroidism (SCH, higher serum thyroid stimulating hormone (TSH) with normal thyroid hormone) is associated with an increased risk of ischaemic heart disease (IHD). Subclinical thyrotoxicosis (SCT, lower serum TSH with normal thyroid hormone) is also associated with an increased risk of atrial fibrillation, cardiovascular morbidity and mortality.

Aim and methods: To examine the relationship between IHD and thyroid disorders in clinical practice. A retrospective evaluation of the prevalence of thyroid disorders including subclinical thyroid disease in patients referred with chest pain to the rapid access chest pain clinic (RACP) was performed. The relationship between thyroid function (TSH) and presence and severity of IHD, as assessed by myocardial perfusion scan (summed stress scores), was assessed.

Results: The records of 2970 patients were analysed. The prevalence of hypothyroidism, thyrotoxicosis, SCH, and SCT was 0.2%, 0.3%, 6.8%, and 1.7% respectively. There were 575 patients with IHD (69% men, median age 63 years) and 795 without (33% men, median age 60 years). The prevalence of SCH in patients with IHD was 6.1% (9.2% women, 4.7% men) and 7.2% (7.4% women, 6.9% men) in patients without. The prevalence of SCT was 1.8% in patients with IHD and 1.6% in those without. There was no difference in prevalence of any thyroid disorders between patients with IHD and without. There was no significant correlation between serum TSH levels and severity of IHD assessed by summed stress scores of myocardial perfusion scans. Incidentally, only 44% of the 78 patients with known thyroid disease were biochemically euthyroid.

Conclusion: The prevalence of subclinical thyroid dysfunction in this RACP was similar to previous epidemiological studies with no difference between patients with IHD and without. We found no association between serum TSH and the severity of IHD. A significant number of patients were not treated adequately for hypothyroidism.