Electrolyte Disorders — Hyperkalemia

Among patients presenting to a tertiary care hospital in India with acute symptomatic hyperkalemia (K⁺ >6.5 mEq/L with ECG changes), what is the most common underlying cause?

Regarding the pathophysiology and ECG manifestations of hyperkalemia, all of the following statements are correct EXCEPT:

Which mechanism of action best explains why calcium gluconate is the first-line agent for acute symptomatic hyperkalemia?

A 58-year-old man with type 2 diabetes mellitus and chronic kidney disease (eGFR 22 mL/min/1.73m²) presents to the emergency department with palpitations and muscle weakness. His wife reports he consumed a high-potassium diet (bananas, oranges, tomato juice) over the past 2 days. On examination, blood pressure is 148/92 mmHg, heart rate 102 bpm. Laboratory investigations reveal: serum potassium 7.2 mEq/L, serum creatinine 3.8 mg/dL, pH 7.28, HCO₃⁻ 16 mEq/L. ECG shows peaked T waves and prolonged PR interval. What is the most appropriate immediate intervention?

A 72-year-old woman with hypertension on lisinopril and a recent diagnosis of acute kidney injury (serum creatinine 2.4 mg/dL, baseline 0.9 mg/dL) is found to have serum potassium 6.8 mEq/L on routine blood work. She is asymptomatic, and ECG shows no acute changes. Urine output is 800 mL/day. What is the most appropriate next step in management?