CIRCADIAN BLOOD-PRESSURE RHYTHM IN HYPERTHYROIDISM AND IN 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 heartrate 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.