Hypernatraemia

OVERVIEW

Hypernatraemia can be caused by a number of critical illnesses

CAUSES

  • water depletion (decreased intake, hypotonic fluid loss – renal/non-renal)
  • solute excess (Na+ or other)

Decreased intake

  • common
  • elderly with altered cognitive function -> inappropriate response to thirst

H2O loss

  • GI loss
  • intrinsic renal disease
  • hypercalcaemia
  • hypokalaemia
  • solute diuresis
  • glucosuria
  • diabetes insipidus (central or nephrogenic)

MANAGEMENT

Goals:

(1) correct H2O deficit
(2) reduce ongoing excessive urinary H2O losses

Calculate water deficit

Water deficit = 0.6 x premorbid weight x [1 – 140/serum Na+]

  • formula assumes TBW = 60% and does not account for ongoing water losses

Treatment

  • treat cause
  • decreased intake: rehydration
  • central DI: DDAVP (1-2mcg) + 5% dextrose to correct H20 deficit
  • nephrogenic DI: Na+ restriction, thiazide diuretics, large doses of DDAVP

References and Links


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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