OBJECTIVES: To examine burden of illness and hospital utilization in patients diagnosed with hyperkalemia. METHODS: A retrospective cross-sectional study was conducted on MedAssets health system data for inpatient and outpatient visits diagnosed with hyperkalemia for the October 2013 to September 2015 timeframe. Age and gender, clinical comorbidities and measures of utilization including number of visits, length of stay (LOS), and readmissions were described. Multivariable regression was used to identify significant drivers of hospital-based utilization. RESULTS: The hyperkalemia population consisted of 374,720 patients across 406 hospitals with a mean age of 64.7. Of 531,341 visits, 60.6% occurred in the inpatient setting.  The most common comorbidities included renal disease (RD 57.8%), diabetes (49.2%), chronic kidney disease (CKD 47.0%), anemia (42.2%), hypertensive CKD (40.5%), and congestive heart failure (CHF 36.6%). When patients were admitted the average LOS was 8.6 days with an average cost of $17,060 and 9.3% 30-day readmission rate. Surgical procedures such as colon diversion (RR=2.3, p<.0001), kidney transplant (RR=1.3, p<.0001), and hemodialysis (RR=1.3, p<.0001) as well as infections (septicemia RR=1.4, p<.0001; pneumonia RR=1.4, p<.0001; Urinary tract infection RR=1.2, p<.0001) and comorbidities (anemia RR=1.2, p<.0001; cardiac dysrhythmia RR=1.1, p<.0001) were associated with longer LOS. Readmissions occurred within 30 days for 9.3% of inpatient admissions with infection (12.4%), CHF (7.5%), and rehabilitation services (6.9%) as the most common primary diagnoses for readmission.  3.2% were readmitted for hyperkalemia. The most common predictors of readmission included severe liver disease (OR=1.4, p<.0001), kidney transplant (OR=1.3, p=.0005), paraplegia/hemiplegia (OR=1.3, p<.0001), anemia (OR=1.2, p<.0001), renal failure (OR=1.2, p<.0001), and CHF (OR=1.2, p<.0001). CONCLUSIONS: Hyperkalemia patients are treated primarily in the inpatient setting and are resource intensive with long lengths of stay, high cost and a high rate of readmission within 30 days.