Abstract: The patient, a 41-year-old woman, was admitted because “it was found out she had elevated serum potassium levels for 18 days”. Eighteen days prior to admission at our hospital, the patient was found to have elevated serum potassium during hospitalization at another hospital, where the patient received symptomatic treatment and was discharged after her serum potassium returned to a normal level. However, the patient still had elevated serum potassium repeatedly and was referred to our hospital for further examination. The patient had a history of acute nephritis and gestational hypertension. Six months prior to admission at our hospital, it was found out that the patient had slightly elevated blood pressure, but no intervention was done. The patient’s father has a history of hypertension and diabetes. After admission, laboratory results showed that the patient had hyperkalemia, hyperchloremia and metabolic acidosis. The level of plasma renin was obviously below the normal range, but the concentration of plasma aldosterone was within the normal range. A new mutation locus (c.1115delG) in KLHL3 (Kelch like family member 3) gene was revealed by genetic testing, leading to the diagnosis of pseudoaldosteronism type Ⅱ (PHA2). The patient was given regular treatment of oral hydrochlorothiazide hydrochloride at set intervals. Subsequently, her blood electrolyte level, blood pH, BE and BEB have returned to normal levels. The patient was followed up for 12 months and did not feel unwell during the follow-up period.