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Rationale & Objective: Both hypo- and hyperkalemia can cause fatal cardiac arrhythmias. Although predialysis serum potassium level is a known modifiable risk factor for death in patients receiving hemodialysis, especially for hypokalemia, this risk may be underestimated. Therefore, we investigated the relationship between predialysis serum potassium level and death in incident hemodialysis patients and whether there is an optimum level. Study Design: Prospective multicenter cohort study. Setting & Participants: 1,117 incident hemodialysis patients (aged >18 years) from the Netherlands Cooperative Study on the Adequacy of Dialysis-2 study were included and followed from their first hemodialysis treatment until death, transplantation, switch to peritoneal dialysis, or a maximum of 10 years. Exposure: Predialysis serum potassium levels were obtained every 6 months and divided into 6 categories: ≤4.0 mmol/L, >4.0 mmol/L to ≤4.5 mmol/L, >4.5 mmol/L to ≤5.0 mmol/L, >5.0 mmol/L to ≤5.5 mmol/L (reference), >5.5 mmol/L to ≤6.0 mmol/L, and >6.0 mmol/L. Outcomes: 6-month all-cause mortality. Analytical Approach: Cox proportional hazards and restricted cubic spline analyses with time-dependent predialysis serum potassium levels were used to calculate the adjusted HRs for death. Results: At baseline, the mean age of the patients was 63 years (standard deviation, 14 years), 58% were men, 26% smoked, 24% had diabetes, 32% had cardiovascular disease, the mean serum potassium level was 5.0 mmol/L (standard deviation, 0.8 mmol/L), 7% had a low subjective global assessment score, and the median residual kidney function was 3.5 mL/min/1.73 m2 (IQR, 1.4-4.8 mL/min/1.73 m2). During the 10-year follow-up, 555 (50%) deaths were observed. Multivariable adjusted HRs for death according to the 6 potassium categories were as follows: 1.42 (95% CI, 1.01-1.99), 1.09 (95% CI, 0.82-1.45), 1.21 (95% CI, 0.94-1.56), 1 (reference), 0.95 (95% CI, 0.71-1.28), and 1.32 (95% CI, 0.97-1.81). Limitations: Shorter intervals between potassium measurements would have allowed for more precise mortality risk estimations. Conclusions: We found a U-shaped relationship between serum potassium level and death in incident hemodialysis patients. A low predialysis serum potassium level was associated with a 1.4-fold stronger risk of death than the optimal level of approximately 5.1 mmol/L. These results may imply the cautious use of potassium-lowering therapy and a potassium-restricted diet in patients receiving hemodialysis.

In the pathogenesis of anti-neutrophil cytoplasm antibodies (ANCA)-associated vasculitis, T cell contribution is indicated by T cell-dependent ANCA production combined with the presence of T cells in inflammatory infiltrates. However, the exact pathogenic role of T cells in ANCA-associated vasculitis remains to be determined. The Th1/Th2 concept is useful for understanding T cell involvement in pathological processes. This review focuses on T cells and particularly the Th1/Th2 paradigm in ANCA-associated vasculitis. Most research has been done in Wegener’s granulomatosis, where a shift in T cell response, from a Th1 pattern in localized disease towards a Th0/Th2 pattern in generalized disease, appears to occur. Although less thoroughly studied, data in Churg-Strauss syndrome and microscopic polyangiitis indicate that these diseases are predominantly associated with Th2 patterns. Further studies elucidating the true nature of the polarization towards Th1 or Th2 in ANCA-associated vasculitis are clearly needed.Copyright © 2003 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]