ACE and Tumor Lysis Syndrome: Hyperkalemia in children is usually caused by impaired excretion of potassium (adrenal or renal insufficiency), and movement of intracellular potassium to the extracellular space (acidosis, diabetes, tumor lysis syndrome, rhabdomyolysis), as well as drugs and toxins (spironolactone, angiotensin-converting enzyme inhibitors, beta blockers and calcium channel blockers).