Hypertension in primary hyperparathyroidism in relation to histopathology

Hypertension in primary hyperparathyroidism (HPT) was previously attributed to hypercalcemia per se or to impaired kidney function. Of 441 consecutive patients operated on for HPT over 24 years, 57% were hypertensive. Preoperative blood pressure remained fairly constant during the study period, despite otherwise markedly changing clinical picture with, latterly, more asymptomatic patients. The preoperative systolic blood pressure (SBP) was significantly correlated to both serum calcium (p less than 0.001) and serum creatinine (p less than 0.05), but not when the influence of age was taken into account in a multiple regression analysis. Other pathogenetic factors in hypertension were therefore probable. When the statistical analysis was adjusted for differences in age and serum calcium, blood pressure was lower in the HPT patients with parathyroid hyperplasia than in those with adenoma (153 +/- 31/90 +/- 14 vs. 163 +/- 29/91 +/- 14 mmHg, p less than 0.01 for SBP). The concept that parathyroid hyperplasia represents a mild (early) form of HPT that may precede adenoma formation is corroborated by our observations, which also indicate that there is no simple cause-and-effect relationship accounting for hypertension in primary HPT.