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Life in the Fast Lane • LITFL • Medical Blog

Emergency medicine and critical care medical education blog

Critical Care Compendium | Electrolyte Abnormalities Summary

Electrolyte Abnormalities Summary

by Chris Nickson, Last updated December 17, 2012

GENERAL APPROACH

  • intake:
  • redistribution:
    output:
    urinary
    non-urinary
    -> upper GI
    -> mid GI
    -> lower GI
    -> other – skin, bleeding, sweat, RRT

POTASSIUM

Hyperkalaemia

  • intake: oral intake, blood transfusion
  • redistribution: acidosis, rhabdomyolysis, tumour lysis
  • output:
    urinary – RTA type 4, renal failure, adrenal insufficiency, DM, K+ sparring diuretics

Hypokalaemia

  • intake: inadequate intake
  • redistribution: alkalosis, hypoMg2+, glucose infusion, periodic paralysis, beta-agonists
  • output:
    urinary – steroids (ex or en), DKA, hyperaldosteronism, Cushings, RTA, diuretics
    non-urinary
    -> upper GI – vomiting
    -> mid GI – fistula
    -> lower GI – diarrhoea
    -> other – sweat, burns, bleeding, RRT

MAGNESIUM

Hypermagnasaemia

  • intake: usually iatrogenic (Mg infusion)
  • redistribution:
  • output:
    urinary – renal failure increases risk of accumulation

Hypomagnasaemia

  • intake: TPN, malabsorption, alcoholism
  • redistribution: insulin, hungry bone syndrome
  • output:
    urinary – RTA, diuretics, polyuria from any cause
    non-urinary
    -> upper GI – NG loss
    -> lower GI – diarrhoea

CALCIUM

Hypercalcaemia

  • intake: Ca2+, vitamin A or D, hypoMg2+, hypovolaemia, TPN
  • redistribution: immobilization, malignancy, hyperparathyroidism, sarcoid, lithium, adrenal insufficiency, endocrine causes (thyrotoxicosis, acromegaly, phaeo)
  • output:
    urinary – thiazides

Hypocalcaemia

  • intake: Ca2+, vitamin D, phenytoin (increased metabolism of vitamin D)
  • redistribution: alkalosis, citrate toxicity, hyperphosphataemia, pancreatitis, tumour lysis syndrome, rhabdomyloysis, decreased bone turnover, hypoparathyroidism, drugs (bisphosphonates, PPI’s, SSRI’s, gentamicin)
  • output:
    urinary – ethylene glycol, cis-platin, protamine, loop diuretics
    non-urinary – bleeding, plasmapheresis, citrate RRT

PHOSPHATE

Hyperphosphataemia

  • intake:
  • redistribution:
  • output: urinary
    non-urinary
    -> upper GI
    -> mid GI
    -> lower GI
    -> other – skin, bleeding, sweat, RRT

Hypophosphataemia

  • intake: malnutrition, phosphate binders, vitamin D, malabsorption, TPN
  • redistribution: refeeding syndrome, insulin in DKA
  • output:
    urinary – diuretics, osmotic diuresis, hyperparathyroidism, proximal tubular dysfunction (Fanconi’s syndrome)
    non-urinary
    -> upper GI
    -> mid GI
    -> lower GI – diarrhoea
    -> other – sweat, burns, sepsis, bleeding

SODIUM

  • different to the rest!
  • must think of mainly redistribution of H2O

To sort out:

(1) Osmolality
(2) Volume assessment
(3) Where is the H2O being lost from?

HYPOTONIC

Hypovolaemic

  • urinary (urinary Na+ high) – diuretics, osmotic diuretics, RTA, salt wasting, mineralocorticoid deficiencies
  • non-urinary (urinary Na low)
    -> upper GI – vomiting
    -> mid GI – pancreatitis, bowel obstruction
    -> lower GI – diarrhoea, bowel preparation
    -> other – skin, bleeding, sweat

Euvolaemic

-> SIADH (most common)
-> psychogenic polydipsia
-> hypotonic IVF therapy
-> adrenal insufficiency
-> hypothyroidism

Hypervolaemic

-> CHF
-> cirrhosis
-> nephrotic syndrome
-> hypothyroidism
-> pregnancy
-> TURP syndrome

ISOTONIC (pseudohyponatraemia)

  • high proteins
  • high lipids

HYPERTONIC

  • glucose
  • mannitol
  • sorbitol
  • radiocontrast
  • advanced renal disease (need to correct osmolality = measured osmolalilty – urea)

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About Chris Nickson

FCICM FACEM BSc(Hons) BHB MBChB MClinEpid(ClinTox) DipPaeds DTM&H GCertClinSim

Chris is an Intensivist at the Alfred ICU in Melbourne and is an Adjunct Clinical Associate Professor at Monash University. He is also the Innovation Lead for the Australian Centre for Health Innovation and the Chair of the Australian and New Zealand Intensive Care Society (ANZICS) Education Committee. He has a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia's Northern Territory, Perth and Melbourne. He has since completed further training in emergency medicine, clinical toxicology, clinical epidemiology and health professional education. He coordinates the Alfred ICU's education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the 'Critically Ill Airway' course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of Lifeinthefastlane.com, the RAGE podcast, the Resuscitology course, and the SMACC conference. His one great achievement is being the father of two amazing children. On Twitter, he is @precordialthump.

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