Nephrology Book

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HyponatremiaAka: Low Serum Sodium

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  1. Definition
    1. Serum Sodium < 135 meq/L
  2. Pathophysiology
    1. Hypoosmolar Hyponatremia is most common
    2. Sodium is the principal osmole
    3. Hyponatremia is a water excess state
  3. Symptoms: Acute Hyponatremia (develops over <24 hours)
    1. Symptom onset when Serum Sodium <125 meq/L
    2. Initial
      1. Nausea
      2. Vomiting
      3. Headache
    3. Later or Severe (Serum Sodium <120 meq/L)
      1. Seizure
      2. Coma
      3. Respiratory arrest
  4. Symptoms: Chronic Hyponatremia (develops over >48 hours)
    1. Lethargy
    2. Confusion
    3. Muscle cramps
    4. Neurologic Impairment
  5. Prognosis: Mortality
    1. Acute hyponatremia (Serum Sodium <120 meq/L): 50%
      1. Mortality associated with cerebral edema
    2. Chronic hyponatremia: 10%
      1. Mortality associated with underlying condition
  6. Approach
    1. Is patient hypervolemic?
      1. See Hypervolemic Hypoosmolar Hyponatremia
    2. Measure Serum Osmolarity
      1. Hyperosmolar Hyponatremia (Serum Osms >300)
      2. Hypoosmolar Hyponatremia (Serum Osms <280)
        1. Hypovolemic Hypoosmolar Hyponatremia
        2. Isovolemic Hypoosmolar Hyponatremia
        3. Hypervolemic Hypoosmolar Hyponatremia
      3. Normoosmolar Hyponatremia (Serum Osms 280-300)
  7. Management
    1. See specific hyponatremia protocols based on Serum Osms
    2. See Hyponatremia Management
  8. References
    1. Kone in Tisher (1993) Nephrology, p. 87-100
    2. Levinsky in Wilson (1991) Harrison's IM, p. 281-84
    3. Rose (1989) Acid-Base and Electrolytes, p. 601-38

Hyponatremia (C0020625)

Definition (MSH)Deficiency of sodium in the blood; salt depletion. (Dorland, 27th ed)
Definition (CSP)abnormally low sodium levels in the blood; salt depletion.
Definition (NCI)Hypernatremia; lower than normal levels of sodium in the circulating blood.
ConceptsFinding (T033)
ICD9276.1
EnglishHYPONATRAEMIA, Hyponatremia, Hyponatremias, LOW SALT SYNDROME, LOW SODIUM SYNDROME, Na deficiency, Salt deficiency, SERUM SODIUM DECREASED, SODIUM BLOOD DECREASED, Sodium deficiency, SODIUM DEPLETION, Sodium Serum Decreased, SYNDROME LOW SALT
Spanishdeficiencia de Na, deficiencia de sal, deficiencia de sodio, hiponatremia
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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