VA ICU report 6.16.17: Hypernatremia

Case summary

47M with mutism p/w AMS, profound weight loss and found to have marked hypernatremia


Take aways

  1. Approach to hypernatremia
    1. Consider free water loss (renal, GI, insensible loss)
    2. Reduced access to free water (dementia)
    3. Hypertonic intake (3% NS, ocean water)
  2. Diabetes insipidus implies impaired urinary water reabsorption and therefore urine osms are inappropriately lower than serum osms.
  3. Treatment
    1. Determine acute versus chronic
    2. Calculate free water detect
      1. If acute correct over 24 hours
      2. If chronic correct 10mEq/day
    3. Reassess frequently

 


Approach to hypernatremia

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Treatment

Principles

The principles of treatment in hypernatremia are similar to those in hyponatremia and therefore it also important to determine:

  • Acute (< 24 hours) versus chronic (> 24 hours)
    • Acute: correct over 24 hours
    • Chronic: correct by 10mEq/24 hours
      • Why? With aggressive repletion of free water, there is a risk of cerebral edema. This risk is less than that of aggressive correction of hyponatremia (–> osmotic demyelination syndrome) but is more likely in patients with higher initial Na
  • Symptomatic versus asymptomatic

Details of correction of chronic hypernatremia 

  • Step 1: use the (1) patients’ weight (2) current sodium and (3) goal sodium (usually 10mEq less than current sodium) to calculate the free water deficit for the day.
  • Step 2: divide the free water deficit/24 hours and infuse D5 H20 at that rate
  • Frequently recheck your Na and adjust your rate by starting back at step 1

*Consider making the patient NPO to ensure accuracy of free H20 intake (especially initially).

*In patients with DI, their free water clearance via the kidneys may be dynamic. Therefore, monitoring the urine osm (along with renal or endocrine) is important.

Concomitant hypovolemia

  • For patients with concomitant hypovolemia obtain second PIV (if possible) and bolus PRN (e.g. soft blood pressures)
    • Separating the treatment of hypovolemia from addressing your free water deficit will help  maintain better control of your sodium correction.

Evernote: https://www.evernote.com/l/AGJ9Y-10PL5JhrWZo1VS1mhJZXVl9jUVZ2I

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