SP141STUDY OF THE ASSOCIATION BETWEEN BONE MINERAL DISORDERS AND INTRADIALYTIC HYPERTENSION IN PATIENTS ON MAINTAINANCE HAEMODIALYSIS

Abstract

Background: Intradialytic hypertension (ID-HTN) affects up to 15% of hemodialysis (HD) patients and is associated with significant risk of hospitalization and death. Abdominal aortic calcification affects 81% of MHD patients with its severity increases with age, duration of dialysis and history of cardiovascular disease (CVD). Mineral Bone Disease (CKD-MBD) related factors such as serum calcium, phosphorus, and parathyroid hormone are strong ly associated with severity of Aortic calcification (AC) in HD patients. FGF-23 level increases progressively in CKD patients, beginning in its early stages achieving the highest values in end-stage renal disease (ESRD) patients, to maintain normal serum phosphate levels. Elevated FGF-23 has been linked with hypertension, left ventricular hypertrophy and increased cardiac mortality in CKD patients, but its role in pathogenesis of ID-HTN via inducing vascular calcification and stiffness remains to be explored. Method(s): This study included sixty ESRD patients on regular HD for more than 6 months, that were classified into two groups; Group (1): forty five ID-HTN prone HD patients who developed episodes of ID-HTN in more than 2/3 of HD sessions done during last 3 consecutive weeks, and Group (2): fifteen hemodynamically stable (S) HD patients, without history of ID-HTN as a control group. To all subjects, laboratory investigations were performed including pre- dialysis serum urea, creatinine, electrolytes, minerals, iPTH and FGF-23. Abdominal aortic calcification score (AACS) was assessed in lateral abdominal radiographs by Kauppila method. Atherosclerosis score (AS) was calculated based on measurement of carotid intima media thickness (CIMT), detection of carotid plaques with or without significant stenosis and measurement of ankle brachial BP index. Result(s): Hypertension prone (HP) patients had significantly longer duration of dialysis and higher AACS compared with hemodynamically stable (S) patients. Serum phosphorus, calcium phosphorus product (CaPhP), iPTH and FGF23 were higher in HP than S patients, but the difference was not statistically significant. There was a statistically significant positive correlation between FGF23 and each of duration of dialysis (P = 0.003) and CIMT (P = 0.043). Moreover, AS had a statistically significant positive correlation with serum calcium (P = 0.009). Conclusion(s): The occurrence of ID-HTN is associated with significantly more advanced vascular calcification and fairly increased levels of humoral MBD mediators involved in this process like FGF23, iPTH and CaPhP. FGF23 significantly correlates with CIMT, possibly indicating its involvement in the atherosclerotic process from the early beginning. It remains to be elucidated whether interventions to control FGF23 rise and other MBD parameters would reduce ID-HTN episodes.