MO788ERYPTOSIS AND PARATHORMONE IN PATIENTS WITH END STAGE RENAL DISEASE TREATED BY HEMODIALYSIS

Abstract

Abstract Background and Aims Eryptosis (Red cell apoptosis) has been recognized as one of the mechanisms that mediate anaemia in patients with chronic kidney disease whether pre or on dialysis. Phosphorus (Ph) and parathormone (PTH) can be considered as uremic toxins which are associated with renal anaemia, and both were suggested to be associated with shortened red blood cell (RBC) life span. We aimed to assess the relation between each of PTH and phosphorus levels and eryptosis in a cohort of patients with end stage renal disease (ESRD) treated by haemodialysis. Method We studied a cohort of 85 patients with ESRD on conventional hemodialysis for at least 3 months. Blood was drawn prior to the mid-week dialysis session. Patients are dialysed on Fresenius 4008s machines. The percent of Annexin V-binding RBCs was assessed by flow cytometry in fresh blood samples and was used to indicate the percent of Eryptotic RBCs. Data were represented as median (interquartile range). Results The study included 85 patients on prevalent hemodialysis for a median of 8 (3-12) years, 52.9% females. Hypertension was the most common cause of ESRD (49.4%). The median hemoglobin was 10.9 (9.3 - 13) gm/dl and most patients received erythropoietin therapy (83/85) at a median dose of 8000 (4000 – 8000 units/weak). The median percent of Annexin V- binding RBCs was 2.3 (1.4 – 4.7%). On multilinear regression analysis, only PTH was independently associated with the percent of Annexin V- binding RBCs (standardized β= 0.630; 95.0% CI: 0.001 – 0.003; p<0.001). Patients were then stratified according to the PTH level into: low PTH (< 150 ng/dl; 25/85, 29.4%), target PTH (150 – 600 ng/dl; 33/85, 38.8%) and high PTH (> 600 ng/dl; 27/85, 31.8%) groups. The 3 groups differed significantly in the percent of Annexin V- binding RBCs (1.2 (0.7-1.7); 2.5 (1.8-3.6) and 4.8 (3.2-5.6) % respectively; p<0.001) (Figure). The percent of Annexin V- binding RBCs was similar in patients with high (>5.5) and target (<5.5 mg/dl) Ph levels (p=0.318). It was higher in patients with above-target CaXPh product (>55) than those with target CaXPh product (<55 mg2/dl2) (5 (2-5.4) % vs 2.3 (4.1 – 1.2) %), yet this was not statistically significant (p=0.068). Conclusion Patients with ESRD treated by hemodialysis express high rates of eryptosis. Parathormone excess in those patients may result in further eryptosis enhancement, and this represents a potential pathogenic mechanism linking hyperparathyroidism with the anemia of CKD. Larger interventional studies are thus warranted to further explore the association between parathormone and eryptosis.