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Abstract: TH-PO297

Incidence and Concurrence of Hyperkalemia and Hyperphosphatemia in a Single Outpatient Dialysis Setting: Long vs. Short Interdialytic Interval

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis


  • Spinowitz, Bruce S., New York Presbyterian Queens, Queens, New York, United States
  • Freitas Serafim, Danielle, New York Presbyterian Queens, Queens, New York, United States
  • Kuo, Rayen, New York Presbyterian Queens, Queens, New York, United States
  • Shoaib, Muhammad, New York Presbyterian Queens, Queens, New York, United States
  • Kuo, Sheng F., New York Presbyterian Queens, Queens, New York, United States

Predialysis hyperkalemia is a common finding in patients receiving intermittent hemodialysis, more common following the long interdialytic interval (LIDI). Monthly laboratory assessments are most often done mid-week, following a short interdialytic interval (SIDI). We examined the occurrence and concurrence of hyperkalemia and hyperphosphatemia in individual patients, SIDI vs. LIDI to determine the sensitivity and specificity of detecting these electrolyte abnormalities following short vs. long intervals.


Serum potassium and phosphorus were measured predialysis after a LIDI which followed a previous mid-week SIDI. We performed a retrospective observational cohort study in this single outpatient dialysis center treating 174 patients aged ≥ 18 receiving dialysis 3 times weekly for at least 3 months. Hypokalemic patients were excluded. Patients were categorized into two groups depending on severity of serum potassium: NK=Normal and mild (3.5-5.4 mEq/L) and HK=Moderate and Severe (≥ 5.5mEq/L). Phosphorus levels were grouped: NP= 2.4-6.5 mg/dL and HP ≥ 6.6 mg/dl. The incidence of these two electrolyte abnormalities and concurrence, with calculations of sensitivity and specificity for elevations noted in SIDI vs LIDI were evaluated.


HK group was noted in 13% of patients (22/170) at SIDI and 21% (36/170) at LIDI, 1.6 times more likely. Only 17 of the 36 patients in the HK group were hyperkalemic at both SIDI and LIDI, 47% sensitivity. Similarly, the sensitivity for detection of hyperphosphatemia SIDI vs LIDI in the HP group was only 50%.


A clinically significant number of patients with predialysis hyperkalemia will go undiagnosed if routine monthly testing is only performed following a SIDI. In view of new, safe and effective potassium binders approved for treatment in adults with chronic hyperkalemia, monitoring of potassium following LIDI should be evaluated on a periodic basis.