[Circadian blood pressure rhythm in hyperthyroidism and primary hyperparathyroidism]

Some secondary forms of hypertension are characterized by an abnormal circadian blood-pressure rhythm. Therefore, the circadian blood-pressure variability was investigated in a prospective study using ambulatory blood-pressure monitoring in patients with hyperthyroidism and in patients with primary hyperparathyroidism. Both endocrine disorders are often associated with hypertension. Out of 17 patients with hyperthyroidism 73% were hypertensive, and out of 15 patients with hyperparathyroidism 80% were hypertensive. The blood-pressure profiles were compared to profiles from controls comprising normotensive subjects and patients with essential hypertension. The patients with hyperthyroidism and hypertension had a blunted circadian blood-pressure curve with only a small nocturnal reduction of systolic and diastolic blood pressure as compared to control patients. In patients with hyperthyroidism and normal blood pressure, the circadian blood-pressure rhythm was normal; however, in these patients the circadian heart-rate curve was blunted. All patients with hyperparathyroidism (with and without hypertension) had a normal circadian blood pressure and heart-rate rhythm. From these observations we conclude that in hyperthyroidism the circadian regulation of blood pressure or heart rate is significantly blunted. The circadian blood pressure and heart-rate curve is normal in primary hyperparathyroidism.