Endocrine Abstracts

Objectives: While evidence for an increased risk of hypertension in both overt hyperthyroidism and overt hypothyroidism is consistent, the relation between subclinical hyperthyroidism and blood pressure has not yet received sufficient attention. We aimed to investigate possible associations of decreased serum thyrotropin levels and subclinical hyperthyroidism with blood pressure, pulse pressure, and the risk of hypertension.

Design: The population-based cross-sectional Study of Health in Pomerania.

Setting: We recruited a sample of general adult population of West Pomerania, a previously iodine-deficient region in Northeast Germany.

Participants: A study population of 4087 subjects (2050 females) without overt hyperthyroidism or increased serum thyrotropin levels was available for the present study.

Main outcome measures: Systolic and diastolic blood pressures were measured three times at the right arm of seated subjects. Systolic and diastolic blood pressures of >140 mmHg and >90 mmHg, respectively, were considered increased. Serum thyrotropin levels <0.25 mIU/l and <0.1 mIU/l were considered decreased and suppressed, respectively.

Results: Multivariable analyses revealed lower adjusted mean values for systolic blood pressure in subjects with decreased (132.9 mmHg, 95%-confidence interval 131.1 to 134.8 mmHg) versus normal serum thyrotropin levels (135.0 mmHg, 95%-confidence interval 134.4 to 135.6 mmHg, P=0.04). The adjusted mean values for diastolic blood pressure and pulse pressure did not differ significantly between both groups. There was also no association of suppressed serum thyrotropin levels with any of the endpoints investigated.

Conclusions: We conclude that subclinical hyperthyroidism as evidenced by decreased as well as suppressed serum thyrotropin levels and serum free thyroid hormone levels within the reference range is not associated with hypertension.