Patients with renal disease often have hyperkalemia because the kidneys have trouble excreting;

Patients with renal disease often have hyperkalemia because the kidneys have trouble excreting potassium.

Explanation:

Hyperkalemia is due to increased blood levels of potassium (K⁺) above 5 mEq/L.  K+ a is predominantly intracellular electrolyte involved in multiple organ functions.

The kidney is the organ responsible for the excretion of K⁺, maintaining the balance of its extracellular concentration. When renal disease exists, K⁺ cannot be excreted by the kidney, it accumulates in the blood and hyperkalemia is produced.