Abstract Introduction and Aims Hyperkalemia (hyperK) is an analytical alteration that frequently occurs in the context of acute kidney injury (AKI) adding morbidity to the patient. We know little about the associated factors and the clinical consequences of this complication in patients with community-acquired acute kidney injury (CA-AKI). The aim of present study was to analyze the predisposing factors and the clinical consequences of the hiperK in patients with CA-AKI. Method The present study is based on a cohort of patients with CA-AKI admitted to the Nephology Service of a third level hospital from January 2010 to February 2015. Hyperkalemia was defined by the laboratory of our hospital as potassium levels above 5.1 meq / L Results A total of 308 patients were included in the final analyses. The mean age was 73,22±13,95 years. 58,4% were men. Charlson comorbidity index (CCI) was 7,16 ±2,7 points. The mean of drugs ingested daily was 7,81±3,66 and the length of stay 12,25±11,69 days. In view of the Etiology of AKI, 69,5% prerenal AKI and 30,5% non-prerenal ones. 212 patients had a history of previous chronic kidney disease (CKD) (68.8%). Hemodialysis (HD) was required in 54 patients (17.15%). 38 patients (12.3%) died during hospital stay. HyperK occurred in 173 cases (56,2 %). Mean potassium was 5,45±1,41 meq/L (95% IC 5,29-5,61) (range 2.65-9.70). There was a significant correlation between potassium and pH (r = - 0.328; p <0,001) as well as between K and CCI (r= 0,284; p <0,001). There was an association between hyperK and intake of potassium-sparing diuretics (p<0,001); ACEI/ARB (p=0,003) and beta blocker (p<0,001). There was no association with CKD nor NSAID intake. Using a multiple linear regression model the equation that predicted serum potassium level was: K = 36,44 – (4,4 x pH) + 0,98 (if intake of potassium-sparing diuretics) + (0.10 x CCI). Potassium level did not influence the length stay. Patients with HyperK required HD in a higher proportion (23.7 vs. 9.6%; p 0.01) and also had higher mortality during hospital stay (15.6 vs. 8.1%; p 0.048). After a follow-up of 971±702 days after hospital discharge, Kaplan-Meier survival curves showed a significant difference (Log Rank (Mantel-Cox): Chi-square 20,1; p< 0,001) between patients with hyperK and patients that did not present it. Conclusion HyperK occurred in just over half of our patients. The potassium level was significantly determined by the previous comorbidity, pH and the intake of potassium-sparing diuretics. HyperK patients required HD and died in a greater proportion during hospital stay than the others. Mortality after discharge was higher in patients who presented hyperK during hospital stay. Appropriate measures must be taken to correct hyperK early in patients with CA-AKI.