Lab Case 151 – Interpretation

An 82 year old man presents with compensated shock. He has HHS , acute on chronic renal failure, pseudohyponatraemia, hyperkalaemia (total body depletion)

Causes: MI, infection, diuretics, CVA, PE

Diagnostic Criteria:

  • serum osmolarity > 320mosmol/L
  • serum glucose > 33mmol/L
  • profound dehydration (elevated urea:creatinine ratio)
  • no ketoacidosis

Treatment goals

correct dehydration (often 6-9 L of H2O loss)
provide insulin
replace electrolytes
correct metabolic acidosis



(1) Calculate corrected Na+

  • if hypernatraemic, the corrected Na+ = measured Na+ + glucose/3
  • monitor this as Na+ changes for glucose

(2) Calculate H2O deficit

  • H2O deficit = 0.6 x premorbid weight x (1 – 140/corrected Na+)

(3) Fluid management in first 24 hours

  • maintenance as D5W at standard rate
  • if hypernatraemic: replace half the H2O deficit over 24 hours using ½ normal saline.

(4) Monitor Na+ closely – should not change more than 10mmol in 24 hours

(5) Replace other electrolytes as required

  • K+ (often require aggressive replacement – 10-20mmol/hr, make sure not anuric)
  • Mg2+
  • PO43
  • Ca2+

(6) Fluid management in second 24 hours

  • when glucose < 15mmol/L -> use D5W @ 100-250mL/hr AND saline
  • keep Na+ between 140-150mmol/L
  • the metabolic acidosis rarely requires specific treatment as responds to volume expansion and insulin therapy.


  • insulin at 0.05 U/kg/h
  • do not allow blood glucose to drop by more than 3 mmol/L/h
  • once glucose <15mmol/L and corrected Na+ 10% dextrose
  • thromboprophylaxis (SCD’s, clexane, TEDS) -> high risk of VTE
  • diagnose cause and treat: infection, compliance, MI, CVA


  • needs management in ICU
  • endocrine/general medical referral
  • family informed

Complication Management

  • delirium -> coma
  • cerebral oedema (prevent by resuscitation with isotonic fluid and slow correction of glucose)
  • seizures (focal and generalized)
  • severe dehydration and shock
  • renal failure
  • thrombotic complications: VTE, stroke, AMI
  • intercurrent events: sepsis, MI, aspiration
  • occlusive events: focal CNS signs, chorea, DIC, leg ischaemia, rhabdomyolysis
  • fluid overload and congestive heart failure
  • metabolic derangement: hypokalaemia, hypophosphataemia, hypomagnesaemia, hypoglycaemia, hyperchloraemia with NAGMA