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.