Hyperkalemia clinical presentation ddx

A patient with Addison's disease shows signs of weakness and EKG changes suggestive of hyperkalemia. What mechanism is most likely causing the hyperkalemia in this patient?

1: Insufficient dietary potassium intake
2: Excessive use of loop diuretics
3: Impaired potassium excretion due to mineralocorticoid deficiency
4: Transcellular shift of potassium into cells