Pulse pressure is determined by subtracting the diastolic blood pressure (bottom number) from the systolic blood pressure (top number). The normal pulse pressure is 40. Lower numbers are seen in shock and congestive heart failure. Higher numbers are seen in heart valve regurgitation, stiff arteries and in hyperthyroidism. The pulse pressure returns to normal when hyperthyroidism is treated. A study published in the European Journal of Endocrinology shows that increased pulse pressure, increased blood pressure and incidental hypertension are not seen in subclinical hyperthyroidism, which is defined as a TSH below 0.25 mu/L and normal FT4 and FT3 levels.
Eur J Endocrinol. 2009 Oct;161(4):615-21. Epub 2009 Jul 6.
Subclinical hyperthyroidism and blood pressure in a population-based prospective cohort study.
Völzke H, Ittermann T, Schmidt CO, Dörr M, John U, Wallaschofski H, Stricker BH, Felix SB, Rettig R.
SHIP/Clinical-Epidemiological Research Unit, Institute of Community Medicine, Ernst Moritz Arndt University of Greifswald, Walther Rathenau Strasse 48, D-17487 Greifswald, Germany. firstname.lastname@example.org
There is current controversy on the association between subclinical hyperthyroidism and hypertension. Data from cohort studies have not been available yet. The present study was designed to longitudinally investigate possible associations of subclinical hyperthyroidism with blood pressure, pulse pressure and the risk of hypertension.
We used data from the population-based, prospective cohort Study of Health in Pomerania and included 2910 subjects (1469 women) aged 20-79 years with completed 5-year examination follow-up. Subjects with increased serum TSH levels or overt hyperthyroidism were excluded. Serum TSH levels below 0.25 mIU/l with free triiodothyronine and free thyroxine levels within the reference range were defined as subclinical hyperthyroidism. Blood pressure was measured according to standard methods.
Multivariable analyses adjusted for age, sex, overweight, obesity, smoking status and time between the examinations did not reveal any statistically significant association between subclinical hyperthyroidism and any of the blood pressure-related variables in the whole study population. Although the 5-year hypertension incidence was higher in subjects with subclinical hyperthyroidism compared with those without (31.4 vs 19.2%; risk ratio 1.64; 95% confidence interval (CI) 1.17-2.28, P=0.006), both groups did not differ with respect to the risk of hypertension, after analyses were adjusted for confounders (relative risk 1.23, 95% CI 0.91-1.68, P=0.182). Analyses yielded similar results in subjects without thyroid disease and in those who took no antihypertensive medication.
Subclinical hyperthyroidism is not associated with changes in blood pressure, pulse pressure or incident hypertension