The circadian variation of blood pressure and heart rate in patients with hyperthyroidism.

Abstract

The circadian variation of blood pressure (BP) and heart rate (HR) was examined in 18 normal subjects, 15 patients with essential hypertension treated with R-blockers and 21 patients with hyperthyroidism. Most of the patients with hyperthyroidism were also treated with /3-blockers. The 24 hr BP was measured with an ambulatory blood pressure monitoring device (UBP-100) every 5 min. A nocturnal fall in BP and HR was observed in the patients with essential hypertension treated with f3-blockers and the patients with mild to moderate hyperthyroidism as well as normal subjects. On the other hand, in patients with severe hyperthyroidism the nocturnal fall was observed in HR alone, and the fall was small in its amplitude. There was a significant negative correlation between triiodothyronine (T3) level and percentage amplitude of the nocturnal fall in systolic BP (n=21, r--0.5, p <0.01). However, this relation was not significant in diastolic BP and HR. These results indicate that excess thyroid hormone may modulate the circadian variation of BP and HR.ambulatory blood pressure monitoring ; circadian rhythm ; heart rate ; hyperthyroidism ; triiodothyronine Hemodynamic changes in patients with hyperthyroidism are characterized by marked increases in cardiac output (CO), heart rate (HR) and a decrease in systemic vascular resistance ; all of which lead to a widened pulse pressure (Klein and Levey 1984). It is assumed that the hyperdynamic circulatory state in hyperthyroidism is caused by several factors such as an augmented metabolic rate as a result of direct effects of thyroid hormone and the increased effects of catecholamines on the heart (Klein and Levey 1984). Although the hemodynamic changes in hyperthyroidism are well known, little information has been available on the long term or circadian variation of blood pressure (BP) and HR.

Ambulatory Blood Pressure Monitoring in Secondary Arterial Hypertension Due to Adrenal Diseases

“…Our data regarding the lack of reduction of the nighttime BP in adrenal hypertension are similar to results reported in the literature in several pathophysiologic conditions, eg, autonomic failure, 30 severe renal failure, 31 PHEO, 5,6,32 hyperthyroidism, 32,33 hyperparathyroidism, 12,34 diabetes mellitus, 35 and Cushing's syndrome 6,7,9,32 . In particular, the nocturnal BP decrease was absent in a majority of patients with adrenal hypertension; these data are in accordance, in part, with results of other studies 5,6,9,32 .…”

Ambulatory blood pressure monitoring in patients with hyperthyroidism before and after control of thyroid function

“…2 Few data on the 24-h BP profile in patients with spontaneous hyperthyroidism have been reported. 8,[10][11][12][20][21][22] Minami et al 20 studied 21 normotensive patients with Graves' disease-induced hyperthyroidism and found a nocturnal fall in BP and HR similar to that observed in patients with essential hypertension. However, the amplitude of the nocturnal fall in BP was reduced in those patients with severe hyperthyroidism.…”

“…Mean nocturnal fall in HR and BP is comparable in patients and controls and is not affected by therapy. 8,[10][11][12][20][21][22] Minami et al 20 studied 21 normotensive patients with Graves' disease-induced hyperthyroidism and found a nocturnal fall in BP and HR similar to that observed in patients with essential hypertension. 9,18,19 Elevation of BP in hyperthyroidism is usually at the expense of SBP.…”

“…Hyperthyroidism is accompanied by several haemodynamic changes that can produce BP elevations 7,9,16,17 or hypertension. 20 Middeke et al 10 reported 14 patients with secondary hypertension due to hyperthyroidism who showed significant lower BP falls during the night as compared with normotensive subjects and patients with hypertension. 1,9,17 These changes are the results of thyroid hormone actions on the heart and cardiovascular system; that is, increasing cardiac inotropy and chronotropy and decreasing systemic vascular resistance.…”

“…These authors suggest that excess thyroid hormone might modulate the circadian variation of BP and HR. 20 Middeke et al 10 reported 14 patients with secondary hypertension due to hyperthyroidism who showed significant lower BP falls during the night as compared with normotensive subjects and patients with hypertension. Patients with hyperthyroidism and hypertension had a blunted circadian BP curve with only a small nocturnal reduction in SBP and DBP as compared with control subjects.…”