Parathormone enhances eryptosis in patients with end stage renal disease treated by hemodialysis.

Introduction: Parathormone (PTH) and phosphorus, which are considered as uremic toxins, are associated with reduced red cell survival, yet with unproven mechanism. We aimed to assess the relation between PTH and phosphorus levels and eryptosis in patients with CKD5d treated by hemodialysis.

Methods: In a cohort of 85 patients with CKD5d treated by conventional hemodialysis, the percent of annexin V-binding RBCs was assessed by flow cytometry to indicate the percent of eryptotic RBCs.

Findings: The median percent of annexin V-binding RBCs was 2.3 (1.4-4.7)%. On linear regression analysis, PTH was independently associated with the percent of annexin V-binding RBCs (β = 0.003; 95% CI: 0.002-0.004; p < 0.001). The percent of annexin V-binding RBCs differed significantly in patients with low PTH (<150 pg/mL; 27/85, 31.8%), target PTH (150-600 pg/mL; 32/85, 37.6%), and high PTH (>600 pg/mL; 26/85, 30.6%) groups (1.24 [0.65-1.85]; 2.46 [1.73-4.05]; and 4.82 [3.45-5.61]%, respectively; p < 0.001). Considering the tertiles of the percent of annexin V binding RBCs, PTH increased significantly from 85 (50.6-273) in the 1st to 298.3 (172.8-606.8) in the 2nd and 827.6 (357.4-1171.3) pg/mL in the 3rd tertiles (p < 0.001). Phosphorus and calcium levels as well as the CaxPh product were similar among the three tertiles (p > 0.05).

Discussion: Patients with CKD5d express high rates of eryptosis. PTH excess in those patients may result in further eryptosis enhancement, and this represents a potential pathogenic mechanism linking hyperparathyroidism with the anemia of CKD.