Archive for the ‘Renal Medicine’ Category

Hyponatremia: acute correction of low sodium   Leave a comment

Sodium deficit (in mmol or mEq)
= body weight(kg) × (target Na – measured Na) × 0.6 (if male, or 0.5 for female)

  • set ‘target Na’ as 120mmol/L in the first 24 hours and calculate volume of solution required to correct Na deficit; infuse over 24 hours; most centres require the actual rate (in ml/h) to be calculated

  • then correct slowly to 130mmol/L in the next 24-48 hours

  • NEVER correct more than 10mmol/L in 24 hours (or 0.5mEq/L/h): patient may develop central pontine demyelinosis

  • use Na 0.9% as far as possible; reserve Na 3% for emergencies eg. coma, seizures, severe confusion, brainstem herniation where rapid correction is required (but never more than 0.5mEq/L/h).

  • in cases of heart/renal failure and volume overload, water restriction is required; consider iv frusemide.

  • asymptomatic chronic hyponatremia: no urgency to correct using iv saline; instead, investigate and address the cause.

Concentration of Na in various forms:
NaCl 0.9%: 154mEq in 1L (ie. normal saline)
NaCl 3%: 513mEq in 1L
NaCl 300mg tabs: 5mEq per tab


What are the common causes of high-anion-gap metabolic acidosis?   Leave a comment

K  etoacidosis (diabetic)
U  raemia
S  alicylates
S  ubstances (ethylene glycol, paraldehyde, isoniazid)
M  ethanol
A  lcoholic ketoacidosis
L  actic acidosis (from sepsis, shock, AMI, seizures, rhabdomyolysis)

M  ethanol
U  raemia
D  iabetic ketoacidosis (DKA)
P  araldehyde
I  soniazid
L  actate
E  thylene glycol
S  alicylates

Three other anion-gap generating organic acids have been recognised:

  • D-lactic acid (short bowel syndrome)
  • 5-oxoproline or pyroglutamic acid (chronic paracetamol use in predisposed subset)
  • propylene glycol (solvent used in several parenteral medications)



  1. AN Mehta, JB Emmett, M Emmett. GOLD MARK: an anion gap mnemonic for the 21st century. The Lancet 2008/9;372(9642):892.
  2. JL Duewall et al. 5-oxoproline (pyroglutamic) acidosis associated with chronic paracetamol use. Bayler University Medical Centre Proceedings 2010;23(1):19-20

Posted July 14, 2010 by absinthemisia in Renal Medicine

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