Blood pressure in relation to serum thyrotropin: the Tromsø study

Abstract

It appears to be an association between hypothyroidism and hypertension. However, the relation between thyroid function and blood pressure within the normal serum thyrotropin (TSH) range is uncertain. In the fifth Tromsø study, which is a population-based health survey, serum TSH and blood pressure were measured. This gave us the opportunity to test the hypothesis of a relation between serum TSH and blood pressure within the normal serum TSH range. In all 5872 subjects (2623 male subjects) not using blood pressure or thyroxine medication were included in the present study. Within the normal serum TSH range (0.20-4.00 mIU/l), there was a significant and positive relation between serum TSH and both systolic and diastolic blood pressure. Within this range, and adjusted for age, body mass index and smoking status, the systolic blood pressure was 1.4 mm Hg and the diastolic 1.6 mm Hg higher in male subjects in the highest versus those in the lowest serum TSH quartile. The corresponding differences in the female subjects were 4.0 and 2.7 mm Hg, respectively. When dividing this cohort in those with systolic (>160 mm Hg) and diastolic (>95 mm Hg) hypertension, serum TSH was higher in the hypertensive subjects, but the differences were only statistically significant for diastolic hypertension (serum TSH 1.88+/-0.82 versus 1.69+/-0.74 mIU/l for male subjects, and 1.79+/-0.78 versus 1.63+/-0.75 mIU/l for female subjects, P < 0.05). In conclusion, there is a modest, but significant positive association between serum TSH and blood pressure within the normal serum TSH range.