Independent effects of blood pressure and parathyroid hormone on aortic pulse wave velocity in untreated Chinese patients

Objective: Whether or not calcium-regulating hormones stiffen arteries independent of blood pressure (BP) is uncertain. We investigated the independent associations of carotid-femoral pulse wave velocity (PWV) with 25-hydroxy-vitamin D [25(OH) D], parathyroid hormone (PTH) and 24-h ambulatory BP in untreated Chinese patients.Methods: Consecutive untreated patients referred for ambulatory BP monitoring were recruited. PWV was measured with a high-fidelity micromanometer and the SphygmoCor software (AtCor Medical, West Ryde, New South Wales, Australia). Serum 25(OH) D and PTH were determined by electrochemiluminescence immunoassay. Analysis of variance, single and multiple regressions were applied for analyses.Results: In 1052 untreated patients (50.7% women; mean age, 51 years), PWV averaged 7.8 m/s, 24-h SBP/DBP 126.5/81.7 mmHg, serum 25(OH) D and PTH 36.0 nmol/l and 61.6 pg/ml, respectively. In multivariable-adjusted analyses, BP (P < 0.001) and PTH (P = 0.012) increased from less than 25th to at least 75th percentile of the PWV distribution. In continuous analyses, PWV independently increased by 0.40/0.23 m/s per 1-SD increment in SBP/DBP (P < 0.001) and by 0.14 m/s for a doubling of serum PTH (P = 0.029). Associations of PWV with BP were tighter than with PTH (P < 0.001). In pathway analysis, the effect of PTH on PWV did not run via serum or urinary calcium (P = 0.65), but PTH had both a direct (P = 0.026) and a BP-mediated indirect effect (P = 0.043) on PWV. In none of our analyses were PWV associated with serum 25(OH) D.Conclusion: Arterial stiffness, as assessed by PWV, independently increased both with BP and with PTH, but BP remains the main driver of arterial stiffening.