Circadian cardiac autonomic nerve dysfunction in primary hyperparathyroidism improves after parathyroidectomy.
BACKGROUND
Primary hyperparathyroidism has been associated with premature death in cardiovascular diseases, but reversibility and background mechanisms are uncertain. This study investigates autonomic nervous function in hyperparathyroidism because disturbances in this respect have been related to increased cardiovascular morbidity.


METHODS
Twenty-one consecutive patients with hyperparathyroidism and 23 matched control subjects without interfering medication underwent electrocardiographic recordings and ambulatory blood pressure (ABP) determination during a 24-hour period. Patients were re-examined at normocalcemia 1 year after parathyroidectomy. Heart rate variability was analyzed in subjects with sinus rhythm and normal atrioventricular conduction; time domain measures were calculated from the RR-intervals, and frequency domain variables were obtained with an autoregressive algorithm, which expressed power distribution (high, low, or very low frequency).


RESULTS
Nocturnal increase in low frequency was blunted in cases versus control subjects (103+/-128 m(2) vs 430+/-171 m(2); P=.03). Very low frequency at nighttime correlated inversely with serum parathormone (r=-0.33; P<.05) and increased postoperatively (P=.03). ABP was higher both at daytime and nighttime (P<.05) in patients and remained unchanged after surgery. Systolic ABP correlated with the parathormone (r=0.47; P<.01).


CONCLUSIONS
Results suggest altered circadian autonomic function in hyperparathyroidism that can improve after parathyroidectomy. Despite elevated blood pressure, ABP shows retained diurnal rhythm, which indicates different pathophysiologic mechanisms behind the 2 predictors of cardiovascular death in hyperparathyroidism.
Nilsson
Inga-Lena
IL
Department of Surgery, Sundsvall Hospital, S-851 86 Sundsvall, Sweden.
Aberg
Jan
J
Rastad
Jonas
J
Lind
Lars
L
D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000209:etiology / Q000503:physiopathology*; D001794:Blood Pressure; D021081:Chronobiology Disorders / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006331:Heart Diseases / Q000209:etiology / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006961:Hyperparathyroidism / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016105:Parathyroidectomy / Q000379:methods*