Electrolyte abnormalities

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    Intravenous fluids

    Key points

    1. Children with any acute illness or condition affecting the input, distribution, or output of electrolytes and/or fluid in the body, are at risk of electrolyte abnormalities
    2. Critically abnormal test results should be acted on in a timely manner.  Errors in sample collection or processing may lead to inaccurate electrolyte values and it is essential to consider the clinical context
    3. Serum electrolyte reference ranges vary with different laboratories.  Use age-appropriate normal ranges from your local pathology service
    4. Electrolyte abnormalities should be corrected by the oral/enteral route when possible


    • Electrolytes in bodily fluids are the ionized (or ionizable) substances dissolved in plasma, interstitial, and intracellular fluids. Water and electrolyte input, along with homeostatic mechanisms, keep each electrolyte within the range required for normal biological processes
    • Under normal circumstances, maintenance electrolyte requirements are met through dietary intake and regulated by the kidneys
    • Any acute illness, surgery or condition affecting the volume or distribution of bodily fluids can cause electrolyte disturbance, particularly abnormal plasma sodium eg dehydration, sepsis, refeeding syndrome, renal dysfunction, gastrointestinal losses, SIADH
    • Medications can also cause electrolyte disturbances by interfering with normal elimination, regulation and distribution of electrolytes in the body


    Approach to an abnormal electrolyte result

    1. Is the result critical? This is based on:
      1. Severity of abnormality (mild to severely deranged)
      2. Symptoms or signs (eg ECG changes) of electrolyte abnormality
    2. Is the measurement accurate?
      • Consider repeating the test if the serum electrolyte level is inconsistent with the clinical context eg haemolysis from difficult sampling resulting in falsely elevated potassium 
    3. What is the cause? 
      • Excess or inadequate input: eg fluid administration, intake of fluid and/or electrolytes
      • Redistribution: fluid and/or electrolytes between body fluid compartments eg nephrosis/cirrhosis
      • Excessive or abnormal losses: fluid and/or electrolytes
      • Medication or disease: impacting on electrolyte homeostasis eg diuretics, laxatives, endocrinopathy, renal tubulopathy
    4. Is it an acute or chronic issue?
      • May impact rapidity of correction
    5. What fluid and electrolyte source(s) is the child receiving?

      Sources of electrolytes in hospitalised children

      Oral / enteral 


      Oral diet (food) 
      Breast milk or oral formula 
      Enteral formula 
      Oral rehydration solution 
      Enteral electrolyte supplements 
      Commercial electrolyte sports drinks

      Intravenous fluids 

      • Maintenance 
      • Drug lines or volumes 
      • Replacement of losses 
      • Fluids used in resuscitation 

      Parenteral nutrition 
      Parenteral electrolyte infusions 
      Medications: penicillins, cephalosporins, vancomycin

      Some blood products (eg albumin) 

    6.  Consider plan for correction and safety of approach used
      • What is the normal range of the deranged electrolyte?
      • How much should you correct? Over what time period? Through what route? What is the risk of overcorrecting?
      • Is additional monitoring or support indicated during (or prior to) correction?  
    7. When multiple electrolyte abnormalities exist, which is the priority?
      • Correction of the most critical electrolyte abnormality should be prioritised eg potassium, ionised calcium
      • Correction of one electrolyte abnormality may improve another eg hypomagnesaemia promotes potassium wasting, and so correcting hypomagnesaemia may improve hypokalaemia
      • Some mineral supplements contain sodium or potassium salts eg phosphate preparations



    Electrolyte monitoring

    • Serum electrolytes should be checked before starting intravenous (IV) fluids in children (except for most elective surgery or anticipated short-lived IV fluids in well children)
    • They should be repeated at least every 24 hours in children where IV fluids are continued at more than 50% maintenance or where the child is at risk for fluid and electrolyte problems
    • Electrolytes may require more frequent checking when children:
      • Are unwell (regardless of whether they are on IV fluids)
      • Are at risk of electrolyte abnormalities
      • Have established electrolyte abnormalities or symptoms suggestive of an abnormality
      • Are on medications known to cause electrolyte imbalance
    • Electrolytes should be checked to assess the effect of any intervention


    General Principles

    • Electrolyte abnormalities should be corrected by the oral/enteral route when possible
    • Consider if current source(s) of electrolyte intake can be dose-adjusted to correct the abnormality or are additional source(s) of electrolyte supplementation indicated?

    See individual guidelines for specific electrolytes
    Intravenous fluids

    Consider consultation with local paediatric team when

    • You are unsure about management of an electrolyte abnormality
    • The electrolyte abnormality is severe
    • The child does not respond to initial management

    Consider consultation with clinical nutrition or gastroenterology team when

    • Children on parenteral nutrition with an electrolyte abnormality

    Consider transfer when

    • The child has critical electrolyte abnormalities
    • The child is symptomatic or requires close monitoring not available in your centre

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval Services

    Consider discharge when

    • The child is clinically stable with an appropriate management plan in place
    • Any acute electrolyte abnormalities have resolved or chronic abnormalities are stable

    Last updated November 2021

  • Reference List

    1. Australian Medicines Handbook Children’s Dosing Companion.  2020.  Australian Medicines Handbook Pty Ltd. Adelaide.
    2. Canada TW, et al.  ASPEN Fluids, Electrolytes, and Acid-Base Disorders Handbook. 2015. American Society for Parenteral and Enteral Nutrition. U.S.A.
    3. Jochum F, et al. ESPGHAN/ESPEN/ESPR/CSPEN guidelines on pediatric parenteral nutrition: Fluid and electrolytes. Clin Nutr. 2018. 37, p2344-2353.  
    4. Rees, L, et al. Paediatric Nephrology (Oxford Specialist Handbooks in Paediatrics), 3rd Edition 2019