Management of hyperkalaemia in children (1 month to 16 years)

• Summary of guideline
• Aims
• Objectives
• Diagnosis
• Causes
• Investigations
• ECG Changes
• Treatment/Management
• Monitoring

Summary of Guideline

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Aims

The aim of this guideline is to help paediatricians, those in secondary care and other allied health care workers detect and manage hyperkalaemia in the paediatric population.

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Objectives

To provide evidence-based recommendations for appropriate diagnosis, investigation and management of hyperkalaemia in paediatric patients aged 1 month - 16 years.
For management of hyperkalaemia in children under 1 month please follow the neonatal guideline.
For management of hyperkalaemia in adults or children aged 16 or over please follow the adult guideline.

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Diagnosis

Hyperkalaemia is defined as a plasma or serum potassium greater than 5.5mmol/L. Severe hyperkalaemia is a potassium greater than 7mmol/L and is a medical emergency and needs immediate attention. The urgency of intervention depends on the level of potassium and how rapidly it is increasing, the presence or absence of symptoms and any electrocardiogram (ECG) findings. The most serious problems caused by hyperkalaemia are cardiac conduction abnormalities and arrhythmias, which are more likely with potassium greater than 7mmol/L or if there has been a rapid change. 

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Causes

Pseudohyperkalaemia

• Haemolysed blood sample
• Sample from arm receiving IV fluids containing potassium
• Marked leucocytosis or thrombocytosis.
• Hereditary spherocytosis and familial pseudohyperkalaemia (potassium leaks from cells due to cooling).
• EDTA contamination of the sample
• Hyperventilation (respiratory alkalosis can cause potassium to move out of the cells).

Increased potassium intake

• High intake due to IV fluids or parenteral nutrition
• Blood transfusion
• Drugs containing high amounts of potassium

Transcellular movement of potassium

• Cellular injury
  • Tumour lysis syndrome
  • Rhabdomyolysis/trauma/burns
  • Severe haemolytic processes
• Metabolic or respiratory acidosis
• Hyperkalaemic periodic paralysis
• Insulin deficiency 
• Drugs e.g. beta blockers

Impaired renal excretion of potassium

• Acute or chronic kidney disease 
  • Hyperkalaemia not usually seen until eGFR is below 30ml/min/1.73m2.
• Dehydration/hypovolaemia
• Decreased activity of renin-angiotensin-aldosterone system
  • Congenital adrenal hyperplasia (CAH)
  • Primary adrenal insufficiency
  • Pseudohypoaldosteronism (condition characterised by renal tubular unresponsiveness or resistance to the action of aldosterone).
  • Type 4 renal tubular acidosis
    • Can be associated with sickle cell disease, urinary tract obstruction or infection
• Medications
  • Potassium sparing diuretics e.g. spironolactone
  • ACE inhibitors e.g. captopril, enalapril, lisinopril
  • Angiotensin 2 receptor blockers e.g. losartan
  • Non-steroidal anti inflammatories (NSAIDs) e.g. ibuprofen
  • Calcineurin inhibitors e.g. tacrolimus, ciclosporin

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Investigations

• Urea and electrolytes
• Calcium, Magnesium, Bicarbonate, Chloride
• Glucose
• Urine analysis
• Consider creatinine kinase (CK), cortisol, aldosterone, renin, hormone precursor levels and a urine steroid profile.

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ECG Changes

All patients should be placed on a cardiac monitor looking for ECG changes of hyperkalaemia.
Conduction abnormalities are more likely if there is a rapid rise in potassium, if the patient is acidotic or has co-existing abnormalities in sodium or calcium.

ECG changes include: Tented T waves Shortened QT interval Prolonged PR interval and QRS duration Flattened P waves Ventricular tachycardia (VT) or sinus bradycardia If severe can lead to ventricular fibrillation (VF) and asystole. If there are any of these features present and/or if serum potassium > 7mmol/L give IV calcium gluconate 10% as a membrane stabiliser: 1month - 18 years: 0.5mL/kg (0.11mmol/kg) Max. 20mL (4.5mmols) Give as a slow IV injection over 5-10 minutes (see the paediatric calcium gluconate IV monograph for dilution and administration details). Repeat after 5 minutes if persistent ECG changes. In a cardiac arrest situation calcium chloride 10% should be used as per the paediatric resuscitation guidelines.

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Treatment / Management

Stepwise Management of Hyperkalaemia

• Assess the patient, including fluid status and ensure intravascularly replete (give fluids +/- furosemide if appropriate).
• Ensure the patient is placed on a cardiac monitor and that calcium gluconate is given (see above) in the presence of ECG changes and/or if serum potassium > 7mmol/L.
• Recheck result with free flowing venous sample. If severe hyperkalaemia (potassium >7.0mmol/L or presence of ECG changes) do not delay treatment to repeat the sample.
• Stop all potassium containing medications or feeds/food.
  Stop or change any potassium raising medications. If in doubt consult your ward pharmacist, consultant or BNF.   
• Correct acidosis (i.e. pH <7.3 or plasma bicarbonate <16) NB any hypocalcaemia must be corrected before correction of acidosis to avoid risk of tetany/seizures
  If the child is acidotic give a single dose of sodium bicarbonate 1mmol/kg orally or IV (see sodium bicarbonate IV monograph for further administration details). Please note IV sodium bicarbonate is incompatible with IV calcium gluconate and should not be administered down the same line.  
• Treat the underlying cause if known.
• Drug treatment of hyperkalaemia (please note this guidance is based on local practice and may differ from the BNFC):

Mild hyperkalaemia: potassium 5.5-6.0mmol/L.

Moderate hyperkalaemia: potassium 6.1-7.0mmol/L with NO symptoms or ECG changes.

Severe hyperkalaemia: potassium >7.0mmol/L and/or a presence of symptoms or ECG changes.

Subsequent Management

1. Consider the addition of calcium resonium if appropriate.

1. For fluid overloaded patients consider the addition of furosemide (1mg/kg (max.40mg) by IV injection) unless the patient is oligoanuric.
2. Consider hydrocortisone (1-2mg/kg (max. 100mg) by IV injection) if suspecting adrenal insufficiency
3. If hyperkalaemia is persistent consider haemodialysis. This should be under guidance from the consultant paediatric nephrologist or PICU.
   
   For paediatric renal patients who are regularly on either peritoneal or haemodialysis consider whether their dialysis should be commenced. Contact the on-call consultant paediatric nephrologist.

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Monitoring

Potassium

• A blood gas should be performed to check potassium after giving the initial treatment and repeated as follows:

Calcium

• Serum calcium should be monitored carefully. Hypocalcaemia must be corrected before correction of acidosis to avoid tetany/seizures that can be precipitated by falling ionised serum calcium.  
• Calcium salts are irritant - monitor the infusion site for signs of extravasation.  

Sodium

• Serum Sodium should be monitored if sodium bicarbonate has been given.

Blood Glucose

• Blood glucose should be monitored every 15-30 minutes for several hours if insulin and glucose therapy has been used.

Fluid Balance
Watch for fluid overload in the presence of renal failure and adjust fluid intake accordingly. Patients require fluid balance and daily weights.