Sat-212 Analysis of Phosphate Clearance In esrd Patients on Hemodialysis

Abstract

Introduction: Hyperphosphatemia has been found to be consistently associated with increased chances of secondary hyperparathyroidism, vascular and valvular calcification, calciphylaxis and cardiovascular morbidity and mortality in end stage renal disease (ESRD) patients. Dialysis dose, nutritional practices and patients' level of education have an impact on maintaining serum phosphate levels and despite all available strategies, controlling serum phosphate levels remains challenging for nephrologists. In our study we assessed the effect of dietary phosphate intake, delivered dialysis dose (Kt/V, online clearance monitoring (OCM), urea reduction ratio (URR) and total weekly hemodialysis (HD) duration on phosphate levels and other factors affecting its clearance. Methods: This study was carried out on 34 ESRD patients on maintenance hemodialysis through an arteriovenous fistula or permanent central venous catheter at our diaysis center in our hospital in Lahore. Patients' name, age, gender, type of dialyzer, membrane surface area, effective blood flow rate and ultrafiltration volume were all recorded. Questionnaires were filled regarding daily phosphorus intake. Blood samples were collected from the arterial end before connecting the arterial line and rinsing the puncture needle; specimens after HD were collected from the arterial line at the end of dialysis; before collection the blood flow rate was reduced to 50 mL/min. Data analysis was done using SPSS version 25. Results: Out of 34 hemodialysis patients, 41% (14/34) of patients were compliant to thrice weekly hemodialysis. There were 16 (47.1%) females and 18 (52.9%) males, age ranging from 17 to 87 and mean age of 59.6 years, with maintenance hemodialysis vintage ranging from half a month to 79 months with a mean vintage of 33.9 months. Mean pre-& post-HD phosphate were 6.01mg/dl and 2.59mg/dl, respectively. There was a significant mean difference in pre-and post-dialysis phosphate levels (p< 0.01). Mean Phosphate Reduction Ratio (PRR) was 55.6%. Patients with a higher PRR had a higher predialysis serum phosphate and urea (r ¼ 0.608, p <0.01 and r ¼ 0.379, p ¼ 0.027 respectively). PRR had a negative correlation with daily phosphate intake (r ¼ -0.377, p ¼0.028). PRR had no significant association with Kt/V, OCM, URR and blood volume passing through the dialyzer, UF volume, residual urine output, use of phosphate binders or hematocrit. The post-dialysis phosphate was lower in patients with higher Kt/V, URR and OCM (r ¼ -0.417 p ¼0.014, r ¼ -0.307 p ¼0.07, r ¼ -0.295 p ¼0.091 respectively).Patients who had a longer weekly time on dialysis had a lower predialysis phosphate levels (r ¼ -0.34, p ¼ 0.049). High pre-dialysis phosphate had a positive correlation with pre-dialysis urea (r ¼ 0.568, p < 0.01) and a negative correlation with serum bicarbonate (r ¼ -0.363, p ¼0.041). Pre-dialysis phosphate was not significantly related to dietary intake or use of phosphate binders. Conclusions: The predialysis phosphate inversely correlated to total weekly dialysis time ra...