1.For patients with low blood potassium must be asked about the application of diuretics before considering the cause according to low potassium. 2.Patients with essential hypertension, ACEI or ARB with diuretics generally will not be out of low potassium, otherwise think of secondary hypertension. 3. In patients with essential hypertension, the degree of low potassium after diuretics is mild, and it will recover soon after stopping the drugs; otherwise, secondary hypertension should be considered. 4. Low potassium does not occur when potassium-preserving and potassium-excreting diuretics are used together.