Hyponatremia Guidelines .. Bring your salt with you !

Hello guys .. here’s one of our New Guidelines Review series in our Blog. It’s about the new Clinical practice guideline on diagnosis and treatment of hyponatraemia released this Month by European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology(ESE) and the European Renal Association – European Dialysis and Transplant Association (ERA–EDTA), represented by European Renal Best Practice (ERBP).

Are you thirsty ? you can’t drink water till the end 😉

First of all let’s get to know the grading system for recommendations, it will be summarized in this picture

grading system of qualityHyponatraemia is a clinical feature in 15–20% of emergency admissions to hospital and defined as a serum sodium concentration <135 mmol/l. It is the most common disorder of body fluid and electrolyte balance encountered in clinical practice.So, Sodium Balance is controlled by total body water level which is controlled by ADH and kidneys which excretes it. Symptoms : Can Range from mild non-specific to life threatening Brain Edema and in the Guidelines they’ve defined severe and moderately severe symptoms, to make it clear

First of all make sure it’s a true Hyponatremia and not Pseudohyponatraemia which occurs with abnormally high levels of lipids or proteins, Regarding True Hyponatremia, there are many ways tocassify it one of them is by osmolality :

  • Isotonic hyponatraemia : hyperglycaemia, mannitol and glycine
  • Hypertonic hyponatraemia : hyperglycaemia-induced hyponatraemia (Dilutional causes)
  • And the most commonly Hypotonic Hyponatremia, check the volume status (although clinical assessment was not specific (30-50%) nor sensitive (50-80%)-: 

Decreased extracellular fluid volume:

  • Renal loss: salt-losing nephropathies, Diuretics, Primary adrenal insufficiency or Cerebral salt wasting
  • Non-renal loss : GI or Skin
  • Third Spacing: Bowel obstruction, pancreatitis, sepsis

Normal extracellular fluid volume

  • Secondary adrenal insufficiency
  • Hypothyroidism
  • High water and low solute intake

Increased extracellular fluid volume

  • Renal, Heart and Liver Diseases


Definitions :

Based on the Level

  • Mild hyponatremia : serum sodium concentration between 130 and 135 mmol/l
  • Moderate hyponatremia : serum sodium concentration between 125 and 129 mmol/l
  • Profound hyponatremia : serum sodium concentration <125 mmol/l

Based on the onset:

  • Acute <48 hrs or 
  • Chronic >48 hrs
  • If hyponatraemia cannot be classified, we consider it being chronic, unless there is clinical suspicion (table 8)


Based on Severity:sxSo now after all of this boring stuff whenever you have a Stable patient with low Na level go with these steps :

  • Role out Hyperglycemia (correction factor 2.4mmol/l for each 100mg/dl) !
  • Send labs : Check Serum osmolality, if low proceed with: Serum urea, serum uric acid, fractional uric acid excretion, Urine Osmolality (ADH indicator), Urine electrolytes, TSH
  • Check for Reversible causes (patient’s medication)

Otherwise if the patient has Hyponatremia with severe symptoms, as they defined,

  • go with I.V. infusion of 150 ml (2ml/kg) 3% hypertonic over 20 min (1D), which will raise the Na level by 1.5-2 mmol/l
  • you can repeat it till you reach a target of 5 mmol/l increase in serum sodium concentration or the patient improves (2D)

It no improvement :

  • Continue I.V. infusion of 2ml/kg of 3% NS aiming for an additional 1 mmol/l/h increase in serum sodium concentration
  • Stop the 3%Hypertonic if the patient improved or the serum sodium concentration increases 10 mmol/l in total or the serum sodium concentration reaches 130 mmol/l, whichever occurs first (because most probably the symptoms are not due to low sodium) (1D)
  • We recommend limiting the increase in serum sodium concentration to a total of 10 mmol/l during the first 24 h and an additional 8 mmol/l during every 24 h thereafter until the serum sodium concentration reaches 130 mmol/l (1D).

If the patient improved :

  • We recommend keeping the i.v. line open by infusing the smallest feasible volume of 0.9% saline until cause-specific treatment is started (1D) (until the guys upstairs finds out the cause)

Hyponatraemia with moderately severe symptoms

  • We recommend starting prompt diagnostic assessment (1D).
  • Stop, if possible, medications and other factors that can contribute to or provokehyponatraemia (notgraded).
  • We recommend cause-specific treatment (1D).
  • We suggest immediate treatment with a single i.v. infusion of 150 ml 3% hypertonic saline or equivalent over 20 min (2D).
  • We suggest aiming for a 5 mmol/l per 24-h increase in serum sodium concentration (2D).
  • We suggest limiting the increase in serum sodium concentration to 10 mmol/l in the first 24 h and 8 mmol/l during every 24 h thereafter, until a serum sodium concentration of 130 mmol/l is reached (2D).
  • We suggest considering to manage the patient as in severely symptomatic hyponatraemia if the serum sodium concentration further decreases despite treating the underlying diagnosis (2D)

Acute hyponatraemia without severe or moderately severe symptoms

  • We recommend starting prompt diagnostic assessment (1D).
  • We recommend cause-specific treatment (1D).
  • If the acute decrease in serum sodium concentration exceeds 10 mmol/l, we suggest a single i.v. infusion of 150 ml 3% hypertonic saline or equivalent over 20 min (2D).

Patients with expanded extracellular fluid

  • We recommend against a treatment with the sole aim of increasing the serum sodium concentration in mild or moderate hyponatraemia (1C).
  • We suggest fluid restriction to prevent further fluid overload (2D).
  • We recommend against vasopressin receptor antagonists (1C).
  • We recommend against demeclocycline (1D).

Patients with reduced circulating volume

  • We recommend restoring extracellular volume with i.v. infusion of 0.9% saline or a balanced crystalloid solution at 0.5–1.0 ml/kg/h (1B).
  • Manage patients with haemodynamic instability in an environment where close biochemical and clinical monitoring can be provided (not graded).
  • In case of haemodynamic instability, the need for rapid fluid resuscitation overrides the risk of an overly rapid increase in serum sodium concentration(not graded).

What shall you do if Hyponatremia got corrected to rapidly !

  • We recommend prompt intervention for re-lowering the serum sodium concentration if it increases >10 mmol/l during the first 24 h or >8 mmol/l in any 24 h thereafter (1D).
  • We recommend discontinuing the ongoing active treatment (1D).
  • We recommend consulting an expert to discuss if it is appropriate to start an infusion of 10 ml/kg body weight of electrolyte-free water (e.g. glucose solutions) over 1 h under strict monitoring of urine output and fluid balance (1D).
  • We recommend consulting an expert to discuss if it is appropriate to add i.v. desmopressin 2 mg, with the understanding that this should not be repeated more frequently than every 8 h (1D).

At the End this was a summary for the guideline and i brought what’s relevant to Emergency care, if you want to read the full text check it out here. I hope this will finds its way in #FOAMed for whoever needs it.

Abdalmohsen Ababtain

Senior Emergency Resident at Saudi Program of Emergency Medicine Riyadh, Saudi Arabia

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2 thoughts on “Hyponatremia Guidelines .. Bring your salt with you !”

  1. Yes i think it was changed based on this study
    Hyponatremia: evaluating the correction factor for hyperglycemia. American Journal of Medicine 1999
    Where Hillier et. al (1999) evaluated 6 healthy subjects, induced hyperglycemia, and measured actual serum sodium levels, finding a sodium correction factor of 2.4mEq/L to be more accurate than the classically taught 1.6mEq/L correction factor from Katz, 1973

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