Causes of Hyperkalemia

Intake: Too much K either oral or IV.

Kidney-related:
Adrenals:
Adrenal Insufficiency
Chronic = Addison's
Adrenal Hyperplasia --> 22 hydroxylase def. (recall that 11 hydroxylase def causes High BP)
AKI
Acute Tubular Necrosis
Renal Tubular Acidosis Type IV
Hypoaldosteronism

Cellular Damage:
Trauma
Burns
Radiation
Rhabdomyolysis
Tumor Lysis Syndrome

Somatic Cell Pump Problems
Digitalis Toxicity: inhibits the sodium potassium pump.
Metabolic Acidosis: inhibits the sodium potassium pump via electrolytic dysregulation

Pseudohyperkalemia: Tying the touniquet too tight on the arm can cause cells to lyze spilling their potassium into the sample and causing a false elevation.