EFFECT OF HYPERPARATHYROIDISM ON ARTERIAL DISTENSIBILITY IN RENAL-TRANSPLANT RECIPIENTS

Background. The cushioning function of the arterial system is altered in patients with end-stage renal failure. The role of hyperparathyroid ism for the altered vessel wall properties of large arteries is not kn own. Methods. To exclude the confounding effects of fluid volume chang es and hypercirculation as well as uremic toxicity on vessel wall prop erties from those of hyperparathyroidism, the present study was conduc ted in 54 normotensive renal transplant recipients with good graft fun ction, three to six months after transplantation. The vessel wall prop erties of the common carotid artery were investigated in 32 of them, w ho had increased plasma intact parathyroid hormone (iPTH) levels (136 +/- 12 ng/liter, SEM), and compared to those of 22 control recipients of same age with normal plasma iPTH levels (34 +/- 4 ng/liter). Arteri al distension was measured by Doppler analysis of the vessel wall move ments, blood pressure was determined by sphygmomanometry. Results. Blo od pressure was 140 +/- 3/85 +/- 2 mm Hg in renal transplant recipient s with hyperparathyroidism, 135 +/- 3/83 +/- 1 mm Hg in patients with normal plasma iPTH levels (NS). There was no difference in enddiastoli c diameter of the common carotid artery (7.4 +/- 0.2 mm) in renal tran splant recipients with hyperparathyroidism as compared with the contro l patients (7.3 +/- 0.2 mm; NS). Renal transplant recipients with hype rparathyroidism had a lower distension (389 +/- 27 mu m vs. 468 +/- 28 mu m, P < 0.05) and distensibility coefficient of the common carotid artery (15.1 +/- 1.1 10(-3)/kPa vs. DC 19.0 +/- 1.0 10(-3)/kPa, P < 0. 01) when compared with the control patients. Multiple regression analy sis showed that the distensibility coefficient of the common carotid a rtery was negatively correlated with age (P < 0.001), mean arterial bl ood pressure (P < 0.05) and plasma iPTH levels (P < 0.05). The effects of plasma iPTH levels were not related to serum calcium concentration s or to differences in the enddiastolic diameter of the common carotid artery. Conclusions. The data suggest that secondary hyperparathyroid ism can affect the cushioning function of larger arteries in patients with end-stage renal failure independently of high blood pressure.