Hyponatremia

1
Hyponatremia

• Kristen Heins Fernandez
• Gyn Onc Rotation
• Block 7/8 2006

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Importance of Hyponatremia

• Most common electrolyte disorder
• Hospital incidence of 15-20
• Especially common in pulmonary/mediastinal
  disorders, CNS infection, and cancer (uterine).
• What is hyponatremia?
• Normal serum Na 135-145 mEq/L
• Hyponatremia lt135 mEq/L
• Usually asymptomatic when above 125 mEq/L
• Severe Hyponatremia lt125 mEq/L
• Pts can develop confusion and seizures 2o to
  cerebral edema

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Work Up determine fluid tonicity

• Hypertonic (Osm gt280) ? hyperglycemia, mannitol
• Isotonic (pseudohyponatremia) ? hyperlipidemia,
  hyperproteinemia (laboratory error)
• Hypotonic (Osmlt260) ? determine volume status
• Hypovolemic - loss of intravascular volume from
  hemorrage or volume depletion from GI loss, renal
  loss or diuretic use.
• Hypervolemic - excess TBW (CHF, liver cirrhosis,
  nephrotic syndrome)
• Euvolemic common in hospitalized pts (SIADH,
  major surgery, stress, trauma)

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Treatment of hypotonic hyponatremia

• Hypovolemic reexpansion of ECF with isotonic
  saline
• Hypervolemic replenish Na and restrict water
  diuretics can also be effective
• Amt of Na to give 125 serum Na x TBW
• TBW 50 of wt for female and 60 for male
• 125-120 x .5x60kg 150mEq Na/day
• Euvolemic water restriction
• CAUTION Central Pontine Myelinolysis from too
  rapid correction (max 12mEq/L in 1st 24 hrs)

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Prevention for future stays

• Fluid Restriction? Hatherhill, et al.,
  Hospital-Acquired Hyponatremia Is Associated with
  Excessive Administration of Intravenous
  Maintenance Fluid. PEDIATRICS Vol. 114 No. 5
  November 2004, pp. 1368-1369 (doi10.1542/peds.200
  4-1666).
• Use Isotonic Saline instead of LR (or other
  hypotonic IVF)? Mortiz, et al., Prevention of
  Hospital-Aquired Hyponatermia A Case for Using
  Isotonic Saline. PEDIATRICS Vol. 111 No. 2
  February 2003, pp. 227-230.
• Bottom Line
• Closely monitor pts IVF
• Stop problems early
• Check serum Na q1 hour if pt has a problem

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References

• Agamanolis, D., Neuropathology An Illustrated
  Interactive Course for Medical Students and
  Residents. http//www.neuropathologyweb.org/chapte
  r6/chapter6dCPM.html
• Craig, S., Hyponatremia, 1/4/2006.
  http//www.emedicine.com/emerg/topic275.htm
• Ewald, G., McKenzie, C., The Washington Manual.
  28th Ed. 1995.
• Saint, S., Frances, C., Saint-Frances Guide to
  Inpatient Medicine. 1997.
• Santoso, J., Coleman, R., Handbook of Gyn
  Oncology. 2001.
• Simon, E., Hyponatremia, 7/19/2006.
  http//www.emedicine.com/MED/topic1130.htm