Pediatr Nephrol (2011) 26:377–384 Step 4: Increase potassium excretion & & & & Sodium bicarbonate, preferably given to patients who are acidotic. In hemodialysis patients with hyperkalemia it has only a moderate effect if given as prolonged infusion [35]. NOTE: a rise in pH can aggravate hypocalcemia. Loop diuretics (furosemide) inhibit the inward transport of potassium via NKCC2 channel in the TAL. Even in chronic hemodialysis patients, treat- ment with loop diuretics may be of value if the patient has some residual renal function [36]. Ion-exchange resins (containing calcium or sodium) aim to keep enteral potassium from being resorbed. More effective if given orally. Enemas should be retained at least 30-60 min. [37]. Onset within 1-2 h, lasting 4-6 h. Renal replacement therapy (RRT) is the ultimate measure in severe hyperkalemia. Hemodialysis (HD) provides a substantially higher potassium clearance (removal of 50-80 mmol of K+ in a 4- h session) than continuous forms of RRT. Contin- uous veno-venous hemofiltration (CVVH) can more satisfactorily provide long-term control of potassium. Choice of method depends on local circumstances and hemodynamics of the patients, as critical ill patients will rarely tolerate HD sessions [38]. In summary and conclusion, the effective and rapid diagnosis and management of acute and chronic hyper- kalemia in children, especially if renal function is impaired, is clinically relevant and can be life-saving. In treatment of moderate to severe hyperkalemia, the combination of medications with different therapeutic approaches is usually effective, and often methods of blood purification can be avoided. In children with severe hyperkalemia and major ECG abnormalities, conservative efforts should be initiated immediately to stabilize the patient, but management should include rapid facilitation of renal replacement treatment. Multiple-choice questions (Answers appear following the reference list) 1) Which is the most important site of K+ secretion in the kidney? a) proximal tubule b) thin descending limb of loop of Henle c) thick ascending limb of loop of Henle d) distal tubule convolute e) cortical collecting duct 383 2) Which drug does not cause hyperkalemia? a) furosemide b) amiloride c) digoxin d) labetalol e) trimetoprim 3) Which of the following clinical conditions typically causes hyperkalemia (answer true or false for (a) through (e)) a) acute renal failure b) acute myocardial infarction c) rhabdomyolysis d) hyperaldosteronism e) Gordon’s syndrome 4) In managing a patient with severe hyperkalemia: (answer true or false for (a) through (e)) a) first aspect of management is to establish the underlying diagnosis b) ECG may show QRS widening c) the patient is invariably vomiting d) in the short term, calcium gluconate may reduce risk of arrhythmias e) ventricular fibrillation and death may occur 5) The mode of action of salbutamol and glucose/insulin is mediated by a) an increase of renal elimination of potassium b) a reduction of intestinal potassium intake c) stabilization of membrane potential d) an increase of potassium shift from extracellular into intracellular compartment e) hypoglycemia 6) In anuric patients, treatment of hyperkalemia a) should include diuretics b) by increasing elimination of potassium via the gut (e.g., by enemas) may be an important option c) is an infrequent problem d) is always associated with cardiac symptoms e) by shifting potassium into the intracellular depart- ment is ineffective References 1. Klevay LM, Bogden JD, Aladjem M, Sandstead HH, Kemp FW, Li W, Skurnick J, Aviv A (2007) Renal and gastrointestinal potassium excretion in humans: new insight based on new data and review and analysis of published studies. J Am Coll Nutr 26:103–110 2. Kemper MJ (2009) Potassium and magnesium physiology. In: Ronco C, Bellomo R, Kellum JA (eds) Critical Care Nephrology, pp 478–482