Hyponatremia: Difference between revisions
Line 138: Line 138:
#Manage the patient as in severely symptomatic hyponatraemia if the serum sodium concentration further decreases despite treating the underlying diagnosis (2D).
#Manage the patient as in severely symptomatic hyponatraemia if the serum sodium concentration further decreases despite treating the underlying diagnosis (2D).


===NOT Severe/Moderately Severe (Including Asymptomatic)===
===NOT Severe/Moderately-Severe (Including Asymptomatic)===
7.3.1.3. We recommend starting prompt diagnostic assessment (1D).
7.3.1.4. We recommend cause-specific treatment (1D).
7.3.1.2. If possible, stop fluids, medications and other factors that can contribute to or provoke hyponatraemia (not graded).
7.3.1.5. 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).
7.3.1.6. We suggest checking the serum sodium concentration after 4 h, using the same technique as used for the previous measurement (2D).
 
'''Adults:<ref>Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. [http://ndt.oxfordjournals.org/content/early/2014/02/21/ndt.gfu040.full.pdf fulltext]</ref>'''
#Start prompt diagnostic assessment and provide cause-specific treatment
#Check serum sodium concentration after 4 hours
#*Aim for a 5 mmol/l per 24-h increase in serum sodium concentration
#*Limit increase to 10 mmol/l in the first 24 h (8 mmol/l during every 24 h thereafter), until a serum sodium concentration of 130 mmol/l is reached
#Manage the patient as in moderately-severe symptomatic hyponatraemia if the serum sodium concentration decreases 10 mmol/l
 
====Step 1====
====Step 1====
Calculate total body water<ref>The hyponatremia formulas do not work so well (Clin J Am Soc Nephrol 2007;2:1110 and Nephrol Dial Transplant 2006;21:1564)</ref>
Calculate total body water<ref>The hyponatremia formulas do not work so well (Clin J Am Soc Nephrol 2007;2:1110 and Nephrol Dial Transplant 2006;21:1564)</ref>

Revision as of 12:54, 5 October 2017

Background

  • Defined as sodium concentration <135meq/L[1]
  • Patients often not symptomatic until <120meq/L although this level varies by patients and may be higher if the change occurred abruptly[2]
  • Generally accepted recommendations are to avoid correction of more than 12 mmol/L/day (0.5mmol/L/hr) to avoid central pontine myelinolysis. Faster correction (1-2mmol/L/hr) is acceptable with 3% hypertonic saline if the patient is seizing.[3]

Clinical Features

Hyponatremia Symptoms by Severity[4]

Severity NOT severe Moderately severe Severe
Symptoms
  • Gait disturbances
  • Falls
  • Concentration
  • Cognitive deficits

Symptoms from Rapid Correction of Sodium

Differential Diagnosis of Hypotonic Hyponatremia (by Volume Status)

Hypovolemic

Renal Causes

  • Thiazide diuretic use
  • Na-wasting nephroathy (RTA, CRF)
  • Osmotic diuresis (glucose, urea)
  • Aldosterone deficiency

Extra-renal Causes

Hypervolemic

Euvolemic

Pseudohyponatremia

  • Hyperglycemia
    • Na+ decreases by 2.4mEq/L for each 100mg/dL increase in glucose over 100mg/dL[7]
  • Displaced sodium in lab specimen
    • Hyperlipidemia
    • Hyperproteinemia

Evaluation

Work-Up

Prior to giving treatment

  • Urine
    • Urinalysis
    • Urine electrolytes
    • Urine urea
    • urine uric acid
    • urine osmolality
    • urine creatinine
  • Serum
    • Chemistry
    • Serum osmolality
    • Uric acid
    • TSH
    • Cortisol

Diagnosis

True serum sodium (corrected) based on serum glucose[8]
Algorithm for hyponatremia diagnosis
  1. Correct for glucose (see table)
  2. Determine volume status
  3. Calculated osm (in true hyponatremia the osm is reduced)

Hypertonic Hyponatremia

Defined as osmolarity > 295mmol/L with the following causes:

  1. Hyperglycemia
    • Sodium decreases by 2.4mEq/L for each 100mg/dL increase in glucose over 100mg/dL[9]
  2. Mannitol excess

Isotonic (pseudo) hyponatremia

Defined as osmolarity > 275-295mmol/L. Often referred to as pseudo hyponatremia because the elevated lipids or proteins interfere with the laboratory sodium reading. The following are common causes:

  1. Hyperlipidemia
  2. Hyperproteinemia

Hypotonic Hyponatremia

Defined as an osmolarity < 275 mmol/L and categorized as hypovolemic, hypervolemic or euvolemic

Treatment by Patient Status

Must have sufficient confidence that the symptoms are caused by hyponatraemia

Severe Symptoms (See Clinical Features)

Adults:[10]

  1. 3% hypertonic saline 150 mL bolus over 20 min
  2. Check serum sodium concentration after 20 min
  3. Repeat infusion of 150 ml 3% hypertonic saline for the next 20 min
  4. Repeat twice or until a target of 5 mmol/l increase in serum sodium concentration is achieved
    • Each 100 mL will raise sodium by ~2 mmol/l
    • In general, 200-400 mL of 3% hypertonic saline is reasonable dose in most adult patients with severe symptomatic hyponatremia, which may be given IV over 1-2 hr until resolution of seizures.

Pediatrics:[11]

  • 2 mL/kg of 3% over 10-60 minutes can be infused with a repeat of up to 3 times.

Moderately Severe Symptoms

Adults:[12]

  1. 3% hypertonic saline 150 mL bolus over 20 min
  2. Start prompt diagnostic assessment and provide cause-specific treatment
  3. Check serum sodium concentration after 1, 6 and 12 hours
    • Aim for a 5 mmol/l per 24-h increase in serum sodium concentration
    • Limit increase to 10 mmol/l in the first 24 h (8 mmol/l during every 24 h thereafter), until a serum sodium concentration of 130 mmol/l is reached
  4. Manage the patient as in severely symptomatic hyponatraemia if the serum sodium concentration further decreases despite treating the underlying diagnosis (2D).

NOT Severe/Moderately-Severe (Including Asymptomatic)

7.3.1.3. We recommend starting prompt diagnostic assessment (1D). 7.3.1.4. We recommend cause-specific treatment (1D). 7.3.1.2. If possible, stop fluids, medications and other factors that can contribute to or provoke hyponatraemia (not graded). 7.3.1.5. 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). 7.3.1.6. We suggest checking the serum sodium concentration after 4 h, using the same technique as used for the previous measurement (2D).

Adults:[13]

  1. Start prompt diagnostic assessment and provide cause-specific treatment
  2. Check serum sodium concentration after 4 hours
    • Aim for a 5 mmol/l per 24-h increase in serum sodium concentration
    • Limit increase to 10 mmol/l in the first 24 h (8 mmol/l during every 24 h thereafter), until a serum sodium concentration of 130 mmol/l is reached
  3. Manage the patient as in moderately-severe symptomatic hyponatraemia if the serum sodium concentration decreases 10 mmol/l

Step 1

Calculate total body water[14]

  • TBW(kg) = Wt(kg) x 0.6 = [Wt(lb) x 0.45] x 0.6 = Wt(lb) x 0.27

Step 2

Calculate mEq deficit

  • (Desired Na - Measured Na) ~ must be ≤ 10

Step 3

Calculate NS rate to be given over 24hr

  • NS rate (cc/hr) = TBW x mEq deficit x 0.27
  • If using 3% sodium chloride (to avoid volume overload) divide above rate by 3.33

Treatment by Type of Hyponatremia

Hypertonic hyponatremia

  • Correct underlying disorder which is often hyperglycemia[15]
  • Often volume depleted due to osmotic diuresis and normal saline provides adequate volume repletion

Isotonic (pseudo) hyponatremia

  • No treatment needed [15]

Hypotonic hyponatremia

  1. Hypovolemic
    • Give NS but be cautious of raising the serum sodium more than 12 mmol/L/day (0.5mmol/L/hr) and causing central pontine demylinosis[3]
  2. Euvolemic[15]
    • Water restrict
    • Treat underlying cause
  3. Hypervolemic
    • Water restriction
    • Diuresis
    • Treat underlying cause

Na Therapy

Max correction 10mEq/L in first 24hr and 18mEq/L in first 48hr (lowers risk of central pontine demylinosis) [16]

Sodium Containing fluid Concentrations
Fluid type Sodium Concentration
1/2 Normal Saline 77 mEq/L
Normal Saline 154 mEq/L
Lactated Ringers 130 mEq/L
3% Saline 513 mEq/L

Disposition

  • Admit if symptomatic or if Na <125mEq/L
  • Manage severely symptomatic patients in "an environment where close biochemical and clinical monitoring can be provided" (e.g. ICU)

See Also

External Links

References

  1. ↑ Upadhyay A, Jaber BL, Madias NE. Epidemiology of hyponatremia. Seminars in Nephrology 2009 29 227–238
  2. ↑ Spasovski G. et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant. 2014
  3. ↑ 3.0 3.1 Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000 May 25;342(21):1581-9.
  4. ↑ Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. fulltext
  5. ↑ Review of Drug-Induced Hyponatremia. Am J Kidney Dis 2008;52:144
  6. ↑ Kate M, Grover S. Bupropion-Induced Hyponatremia. General Hospital Psychiatry Volume 35, Issue 6, November–December 2013, 681-683.
  7. ↑ Hillier TA, Abbott RD & Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. American Journal of Medicine 1999 106 399–403
  8. ↑ Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. fulltext
  9. ↑ Hillier TA, Abbott RD & Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. American Journal of Medicine 1999 106 399–403
  10. ↑ Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. fulltext
  11. ↑ Moritz ML, Ayus JC. 100cc 3% sodium chloride bolus: a novel treatment for hyponatremic encephalopathy. Metab Brain Dis. 2010 Mar; 25(1): 91-6.
  12. ↑ Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. fulltext
  13. ↑ Spasovski et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant (2014) 0: 1–39. fulltext
  14. ↑ The hyponatremia formulas do not work so well (Clin J Am Soc Nephrol 2007;2:1110 and Nephrol Dial Transplant 2006;21:1564)
  15. ↑ 15.0 15.1 15.2 Schrier RW, Bansal S. Diagnosis and management of hyponatremia in acute illness. Curr Opin Crit Care 2008;14:627-34
  16. ↑ Nagler EV1, Vanmassenhove J, van der Veer SN et al. Diagnosis and treatment of hyponatremia: a systematic review of clinical practice guidelines and consensus statements. BMC Med. 2014 Dec 11;12:1
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