Patient Presentation
A 7-year-old male came to the emergency room with swelling and pain of his right arm. He was known to have chronic renal insufficiency secondary to prune belly syndrome. He was receiving hemodialysis three times weekly and had already had several catheter replacements because of thrombosis and sepsis in the past. The swelling of the upper inner arm began about 12 hours previously and was overlying his current catheter site. Since that time he had increased swelling of the area and forearm. He also had increased pain. He had no fever, chills, emesis, diarrhea, rashes, or cough and he denied any obvious trauma. His last dialysis was 6 days ago because he had missed a session due to his poor social situation. He denied any palpitations, muscle weakness or tetany. The past medical history of thrombosis of catheters, sepsis, and electrolyte abnormalities because of missing medication. He had chronic anemia, short stature, and chronic lung disease additionally. The social history showed that the family was non-compliant with medications and had missed 3 dialysis appointments in the past, but never two treatments in a row though.

The pertinent physical exam showed a short male with obvious swelling of his upper right arm overlying his catheter site. His blood pressure was 138/82, pulse 98, respiratory rate of 24 and he was afebrile. His weight was 4 kilos above his dry weight. Pulsations in the catheter could not be felt and muffled sounds were heard at the ends of the catheter on auscultation. There was some mild redness and warmth but mainly it appeared swollen. There was no obvious trauma to the extremity. His heart was regular rate and rhythm without murmurs. His abdomen was soft without much musculature.

The diagnosis of probable hemodialysis catheter malfunction was made and confirmed by fluoroscopy. The laboratory evaluation showed numerous electrolyte abnormalities including his potassium at 7.6 mEq/L. An ECG showed mild elevation of his T waves. He was admitted to the Pediatric Intensive Care Unit for chronic renal insufficiency, hyperkalemia and electrolyte abnormalities, catheter thrombosis, hypertension and fluid overload. He was treated with a calcium infusion, salbutamol nebulizer and glucose and insulin infusion initially. He also was started on sodium bicarbonate later which improved his potassium to 5.9 mEq/L over several hours. After seeing stabilization of his potassium, he was taken to the operating room and a new catheter placed. Hemodialysis could be restarted soon after which helped to also stabilize his overall condition, including normalization of his potassium and other electrolyte abnormalities. Before discharge, social services and the dialysis team made a new contract with the immediate and extended family with plans for intervention if the patient failed to come for his hemodialysis appointments. He was then discharged to home.

Discussion
Potassium (K+) is an alkali metal (Group 1 of periodic table with Hydrogen, Lithium and Sodium) with an anatomic number of 19. Its chemical symbol K, comes from the medieval Latin, kalium which means potash (mainly potassium carbonate or potassium hydroxide), the substance it was first isolated from.

Potassium is an important cation and it mainly resides in the intracellular fluid with only a small amount in the extracellular fluid. Potassium regulates cell volume, pH and enzyme functions. Hyperkalemia is defined as a potassium level > 5.5 mEq/L in children and > 6.0 mEq/L in newborns.

Hyperkalemia increases cellular membrane excitability and can cause significant problems with the myocardium, resulting in potentially lethal dysrhythmias. The problem is that hyperkalemia can be completely asymptomatic for the patient and even on ECG. First ECG changes are peaked T waves occurring around > 5.6 mEq/L. With increased K+ levels, the PR interval prolongs and the QRS complex becomes widened. Physical symptoms due to hyperkalemia include muscle weakness, reduced deep tendon reflexes, and paresthesias. Symptoms of the underlying disease obviously also occur.

Hyperkalemia is a medial emergency because of its cardiac problems. Treatment is started if there is electrocardiographic changes or serum K+ > 6.0-6.5 mEq/L. K+ levels > 6.0 mEq/L are common in neonates and young children due to pseudohypokalemia (i.e. hemolysis caused by venipuncture or capillary sampling) and a free-flowing blood sample should be re-evaluated if pseudohypokalemia is suspected.

Treatment of the underlying disease process is the most important. Reviewing other causes such as drugs or intravenous fluids which may increase the K+ is also important. Acute management is usually centered on changing the equilibrium quickly to move K+ intracellularly and to stabilize the myocardium. This buys time until other treatments can be implemented or can take effect.

If hyperkalemia is diagnosed, an ECG should be done along with other laboratory testing for underlying causes of hyperkalemia including a complete blood count, complete metabolic panel, glucose and glycosylated hemoglobin, lactic dehydrogenase, uric acid, creatine kinase, urine for blood, hemoglobin and ketones, and others such as renin, angiotensin, aldosterone, cortisol, 21-hydroxylase, 17-OH progesterone and 11-beta-hydroxylase.

A review of hypokalemia can be found here.

Learning Point
The differential diagnosis of hyperkalemia and treatments includes:

• Increased input
  • K+ supplements – oral or intravenous
  • Sodium substitutes – are often K+ based
  • Increased K+ rich foods – bananas, potatoes, beans, grains
  • Blood transfusion
  • Leukocytosis or thrombocytosis
  • Treatment: Decrease input
    • Stop any K+ containing intravenous fluids or oral supplements
    • Use fresh or washed blood for transfusion
• Redistribution of K+ to extracellular space
  • Pseudohypokalemia – very common in children due to sample hemolysis
  • Drugs – beta blockers,
  • Exercise, strenuous
  • Hyperkalemic periodic paralysis
  • Insulin deficiency – diabetic ketoacidosis
  • Intravascular hypoosmolality
  • Intravascular volume depletion
  • Metabolic acidosis
  • Tissue breakdown
    • Chemotherapy and tumor lysis syndrome
    • Hemolysis
    • Hyperthermia
    • Rhabdomyolysis
    • Sepsis
    • Trauma and burns
  • Treatment: K+ redistribution to intracellular space
    • Calcium infusion
      This stabilizes the cellular membrane and increases the membrane resting potential (hyperkalemia does the opposite). 10% calcium gluconate, 0.5 ml/kg or 0.11 mmol/kg given by slow IV infusion over 5-10 minutes. Effects last 30-60 minutes only.
    • Insulin and Glucose infusion
      Insulin drives K+ intracellularly by exchanging Na+ extracellularly.
      Glucose infusions increase endogenous insulin secretion. “Insulin infusion will only need to be started when blood glucose is over 10 mmol/l.” Glucose infusion may be enough.
      Insulin can be infused at 0.1-0.6 units/kg/hour in neonates, or 0.05-0.2 units/kg/hour for > 1 month olds, ALONG WITH, a glucose infusion of 0.5-1 g/kg/hour (= 5-10 ml/kg/h of 10% glucose). Onset of action is ~15 minutes and can last for hours but glucose needs to be monitored closely as hypo- and hyper-glycemia can occur.
    • Sodium bicarbonate
      Metabolic alkalosis causes hydrogen ions to move extracellularly, with K+ moving intracellularly to compensate.
      Sodium bicarbonate 1 mmol/kg over 10-15 minutes OR correct half of the base excess (0.3 x weight x BE). Action onset is about 1 hour and can last for 2 hours. This can cause other electrolyte abnormalities such as hypernatremia and hypocalcemia.
    • Beta-adrenergic agonists
      Beta agonists increase cellular membrane activity and drive K+ intracellularly in exchange for Na+ moving extracellularly. Nebulized or intravenous salbutamol are the most commonly used. Onset is quick with effects lasting up to 2 hours. Dosing can be repeated as needed and tachycardia is the main side effect.
• Decreased output
  • Acute/chronic renal disease
  • Dialysis, inadequate or missed treatment
  • Decrease arterial blood flow
  • Hypoaldosteronism
    • Congenital adrenal hyperplasia
    • Aldosterone synthase deficiency
  • Aldosterone resistance
    • Pseudohypoaldosteronism
    • Distal renal tubular acidosis (Type IV)
      • Sickle cell anemia
      • Urinary tract obstruction/reflux
    • Drugs
      • ACE inhibitors
      • Cyclosporin
      • K+ sparing diuretic
      • Non-steroidal anti-inflammatory drugs
  • Treatment: Increase Output
    • Loop diuretics
      Work by directly increasing urinary K+ excretion and decreasing resorption of K+ and Na+. It is helpful for hyperkalemia due to congestive heart failure or hypoaldosteronism. Furosemide 1 mg/kg intravenously over 5 minutes can be given. Avoid rapid administration. Patients with renal failure may need additional dosing.
    • Cation exchange resins
      They bind potassium in exchange for calcium in the gut. It can be given orally or rectally but doesn’t taste very good and the K+ exchange occurs slowly over 1-2 hours. It can also cause electrolyte abnormalities and should be used with caution especially in very young children. It can remove 0.5-1 mmol of K+ for each gram of resin. Dosing depends on age and administration site.
    • Dialysis
      Is used often when other methods of removal fail however the K+ reduction is seen almost immediately and can be sustained for long periods of time. Hemo- or peritoneal dialysis can be used.

Questions for Further Discussion
1. What is prune belly syndrome and how is it diagnosed?
2. What is the life span of patients with prune belly syndrome?
3. What are indications for social service intervention in patients with chronic disease?

Related Cases

Disease: Hyperkalemia | Potassium

Symptom/Presentation: Abnormal Laboratory Test | Mass or Swelling

Specialty: Emergency Medicine | Nephrology / Urology | Critical Care

Age: School Ager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Potassium

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1653-1654.

Masilamani K, van der Voort J. The management of acute hyperkalaemia in neonates and children. Arch Dis Child. 2012 Apr;97(4):376-80.

Hollander R, Mortier G, van Hoeck K. Hyperkalemia in young children: blood pressure checked? Eur J Pediatr. 2016 Dec;175(12):2011-2013.

Fordjour KN, Walton T, Doran JJ. Management of hyperkalemia in hospitalized patients. Am J Med Sci. 2014 Feb;347(2):93-100.

Potassium. Wikipedia. Available from the Internet at https://en.wikipedia.org/wiki/Potassium (rev. 6/8/18, cited 7/6/18).

Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa