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Hyponatraemia

Prevalence
Causes
Clinical features
Investigations
Therapy
Prognosis
Investigations
  • urea and electrolytes, creatinine a
  • glucose d
  • serum osmolality a
If indicated d
  • cortisol
  • thyroid function tests
Consider sending
  • a urine sample for biochemistry
    • urine sodium c   
    • urine chloride c  
    • urine creatinine c  
    • urine osmolality c
Calculate
  • the fractional excretion of sodium c    
    [Urine Na x Plasma creatinine]/[Plasma Na x Urine creatinine] x 100

  • the fractional excretion of chloride   c  
    [Urine Cl x Plasma creatinine]/[Plasma CL x Urine creatinine] x 100

Expiry date: September 2005
Levels of Evidence used in grading these guides

Authors   T   Ringrose , CM   Ball
Reviewer   J V   Bonventre
CAT Writers   T   Ringrose , CM   Ball