Long-Term Effects of Parathyroidectomy on Hypertension Prevalence and Circadian Blood Pressure Profile in Primary Hyperparathyroidism

Our aims were to evaluate the prevalence and outcome of hypertension in patients with primary hyperparathyroidism (PHPT), previously and after follow-up of parathyroidectomy. A group of 46 consecutive patients with sporadic PHPT due to adenoma undergoing surgery were followed an average of 3.5 years (range 36 to 53 months). In 16 nonselected, consecutive parathyroidectomized patients, with normalized biochemical measurements, circadian rhythm of blood pressure was evaluated with ambulatory blood pressure monitoring (ABPM). Prevalence of hypertension in PHPT was 54.35%, and there was no significant association of PTH, total and ionic calcium levels with SBP and DBP. During follow-up, none of the patients with presurgical hypertension became normotensive and five of the normotensive patients developed clinical hypertension. In ABPM, 6/11 hypertensive and 3/5 normotensive subjects showed nondipper behavior. Serum total calcium was significantly related to night-time systolic blood pressure (SBP) (r = 0.620, P < 0.02), and night-time diastolic blood pressure (DBP) (r = 0.758, P < 0.002). In dippers, creatinine clearance was significantly higher (91.3 +/- 18.5 vs. 64.3 +/- 11.5 ml/min, P < 0.01), while serum total calcium was lower (2.42 +/- 0.13 vs. 2.23 +/- 0.17 mmol/L, P < 0.04) than in nondippers. In conclusion, our results suggest that parathyroidectomy has little effect on hypertension prevalence. Renal impairment, a condition that did not improve after parathyroidectomy, may be a causal factor of hypertension in PHPT. Also, the high prevalence of nondipper behavior in hypertensive and normotensive subjects after parathyroidectomy, suggests that target organ risk persists. We hypothesized that slight elevations of serum total calcium even in the normal range could be involved in the alteration of the circadian rhythm of blood pressure.