## Chronic/Asymptomatic Hyperkalemia Management **Key Point:** Sodium polystyrene sulfonate (cation exchange resin) is the drug of choice for chronic or asymptomatic hyperkalemia without ECG changes. It binds potassium in the colon and increases faecal excretion over 4–24 hours, making it ideal for stable patients who do not require immediate cardioprotection. ### Pathophysiology in This Case This patient has **asymptomatic hyperkalemia** (K⁺ 6.2 mEq/L) with a **normal ECG**, indicating no acute cardiac toxicity. Her hyperkalemia is likely due to ACE inhibitor use (lisinopril) in the setting of reduced GFR, which decreases aldosterone-mediated K⁺ excretion. She does not need immediate membrane stabilization. ### Sodium Polystyrene Sulfonate (SPS) | Feature | Detail | |---------|--------| | **Mechanism** | Cation exchange resin; exchanges Na⁺ for K⁺ in the colon | | **Onset** | 4–24 hours (oral); 2–12 hours (rectal) | | **Potassium reduction** | 0.5–1.0 mEq/L per dose | | **Dosing** | 15 g PO 3–4 times daily; or 30–50 g PR as enema | | **Indication** | Chronic, mild-to-moderate, asymptomatic hyperkalemia | | **Advantage** | No systemic absorption; safe in renal failure | | **Caution** | Constipation; risk of sodium overload (give with sorbitol) | **High-Yield:** SPS is the **only resin-based agent** approved for chronic hyperkalemia management in India and is widely used in CKD patients on ACE inhibitors or ARBs. ### Clinical Pearl In this patient, **discontinuing or reducing lisinopril** should also be considered, as ACE inhibitors are a major cause of hyperkalemia in CKD. However, the question asks for the drug of choice, which is SPS for chronic management. **Mnemonic:** **SPSR** — **S**odium **P**olystyrene **S**ulfonate for **R**enal failure (chronic hyperkalemia).
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