Abstract Background and Aims hyperkaliemia is highly prevalent among chronic kidney disease (CKD) patients and its management is determinant to allow the maintenance of therapies of demonstrated cardiovascular and renal benefit. Attitude towards hyperkaliemia is variable among different guidelines and also among different clinicians. The aim of this study was to analyze nephrologist response to K serum levels > 5.5 mmol/l in the out-patient setting. Method multicentric cross-sectional study performed in the nephrology departments of Madrid analyzing the therapeutic approach to K serum levels > 5.5 mmol/l between July 1st and December 11th, 2022. The only exclusion criteria were being on renal replacement therapy and not obtaining patient's informed consent. Results 13 centers entered the study including 339 patients with hyperK; 331 had enough data to be included in the final analysis. 258 (78%) patients had mild hyperK (5.5-5.9), 60 (18.1%) moderate (6.0-6.4) and 13 (3.9%) severe hyperK (≥6.5). 70.7% were males, mean age 72.0 (SD 13.4) and 87.3% and 55.6% suffered hypertension or DM, respectively. 17.3% were diagnosed from heart failure (25% NYHA type I, 63.6% TII and 11.4% TIII). Most frequent CKD diagnoses were CKD+DM 36%, nephroangioesclerosis/vascular 25.4%, glomerular 7.2% and unknown 16.6%. Median eGFG was 29.9 ml/min/1.73m2 IQR [21-41] and 40.9% had UACR > 300 mg/g. Distribution according GFR stages was homogeneous (Pearson chi2 6.4 p 0.6) Percentage of use of ACEi, ARBs, MRA and NRAi was 41.5%, 37.9%, 13.7% and 1.52% and showed no association with higher K levels. 33.6% of the patients that suffer hyperK were already on any kind of low K diet, and 24.9% were on any K-binding therapy (11.2% calcium polystyrene sulfonate (CPS), 8.2% patiromer and 11.2% sodium zirconium cyclosilicate (SZC)). After hyperK episode, low-k diet was advised in 63.9% and was reinforced in 48% of patients that were already on low-k diet. Detection of hyperK was followed by initiation of k-binding therapy in 46.5% of the patients (22.8% SZC, 13.2% patiromer and 10.5% CPS). Treatment with ACEi or ARBs was stopped or decreased in 17.5% and 13% of patients respectively and in 45% of patient on MRA, with higher percentage of drug discontinuation in severe hyperK (40%, 25% and 50% respectively) Conclusion Most patients in nephrologist out-patient clinic suffering from hyperK are on any RAASi treatment, more than one third on low-k diets and almost 25% are on any k-binding therapy. Hyperkaliemia was followed of dietary advise in a high proportion of patients followed by initiation of k-binding drugs. There is still a high proportion of RAASi discontinuation or dose decreasing after hyperK, especially after severe episodes