Chemotherapy and Potassium: Hypokalemia and Hyperkalemia Risks

Chemotherapy can disrupt potassium homeostasis bidirectionally:

Hypokalemia (K⁺ <3.5 mEq/L)

• GI losses: Vomiting/diarrhea (chemo-induced mucositis, enterotoxicity).
• Renal losses: Cisplatin, ifosfamide → tubular damage → K⁺ wasting (Fanconi-like).
• Intracellular shift: β-agonists, insulin, alkalosis, G-CSF.

Hyperkalemia (K⁺ >5.0 mEq/L)

• Tumor lysis syndrome (TLS): Rapid cell lysis → K⁺, phosphate, uric acid release (high-grade lymphomas, leukemias).
• Renal impairment: Chemo nephrotoxicity (cisplatin, methotrexate) → reduced excretion.
• Adrenal insufficiency: Bilateral adrenal mets or hemorrhage (rare).
• Potassium-sparing diuretics, ACEi/ARB, heparin.

Monitoring & Management

• Serial electrolytes (q1–3 days during intensive chemo; daily during TLS risk).
• IV/oral replacement for hypokalemia; restrict intake + kayexalate/insulin-glucose/dialysis for hyperkalemia.
• Prophylaxis: Allopurinol/rasburicase, hydration for TLS.