Augmentation of central arterial pressure in mild primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is associated with increased cardiovascu lar risk, although the mechanisms involved remain unclear. Recent evidence has shown increased pulse pressure to be a powerful predictor of cardiovasc ular events. As increases in pulse pressure are due largely to arterial sti ffening, we measured arterial stiffness in 21 subjects with PHPT (18 women and 3 men; 46-71 yr old) and 21 age- and sex-matched healthy controls using pulse wave analysis, a technique that measures peripheral arterial pressur e waveforms and generates corresponding central aortic waveforms. This allo ws determination of the augmentation of central pressure resulting from wav e reflection and augmentation index, a measure of vessel stiffness. Metabol ic parameters were also measured. The serum calcium level among PHPT subjects was (mean +/- so) 2.74 +/- 0.14 mmol/L. pulse wave analysis showed that both augmentation and the augmenta tion index were significantly higher in the PHPT group vs, controls [16 +/- 5 vs. 10 +/- 4 mm Hg (P < 0.001) and 36 +/- 9% vs. 25 +/- 6% (P < 0.001)] despite comparable brachial systolic pressures between groups (136 +/- 13 v s. 134 +/- 18 mm Hg). Patients with PHPT had higher fasting serum insulin l evels [median (range), 15.8 (7.4-39.4) us. 11.6 (5.1-23) mU/L; P < 0.05] an d triglyceride (1.6 +/- 0.6 us. 1.2 +/- 0.4 mmol/L; P < 0.05), but lower hi gh density lipoprotein cholesterol (1.4 +/- 0.4 us. 1.6 +/- 0.3 mmol/L; P < 0.05). These data indicate that subjects with mild PHPT (calcium, < 3.0 mmol/L) ha ve increased arterial stiffness, as evidenced by higher augmentation of cen tral aortic pressures. Enhanced vessel stiffness may arise from a combinati on of structural and functional vascular changes due to hypercalcemia and/o r metabolic abnormalities. Increased vascular stiffness in subjects with PH PT may account in part for the increased cardiovascular risk in this group.