II. Physiology: Sodium homeostasis

III. Interpretation: General

  1. Normal: 135-145 mEq/L
  2. Abnormal
    1. Hypernatremia
      1. Serum Sodium over 145
    2. Hyponatremia
      1. Serum Sodium under 135

IV. Interpretation: Corrected Serum Sodium for Glucose

  1. Glucose draws water into the intravascular space via osmotic pressure, and dilutes Serum Sodium
    1. Measured Serum Sodium in hyperglycermia is a true Hyponatremia
    2. However the Serum Sodium corrects with normalization of Glucose
  2. Katz Formula
    1. Adjust measured Serum Sodium (sNa) upwards by 1.6 meq/L per 100 mg/dl increase in plasma Glucose
    2. Corrected Serum Sodium = sNa + 0.016 * (Serum Glucose - 100)
    3. Katz (1973) N Engl J Med 289(16): 843-4 [PubMed]
  3. Hillier Formula
    1. Alternative equation suggests correction should be 2.4 meq/L per 100 mg/dl increase in plasma Glucose
    2. Corrected Serum Sodium = sNa + 0.024 * (Serum Glucose - 100)
    3. Although Hillier equation is thought more accurate, Katz equation is used most commonly
    4. Hillier (1999) Am J Med 106(4): 399-403 [PubMed]

V. Resources

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Ontology: Serum sodium measurement (C0523891)

Definition (NCI) A quantitative measurement of the amount of sodium present in a sample of serum.
Definition (ALT) Analyzing a client/patient's blood, hair, urine and/or other sample to assess his or her serum sodium levels. Service is billed per test.
Concepts Laboratory Procedure (T059)
SnomedCT 166691007, 143995000, 104934005
CPT 84295
English serum Na+, Serum Sodium Measurement, serum sodium measurement (lab test), serum sodium measurement, Sodium; serum, plasma or whole blood, SODIUM SERUM PLASMA OR WHOLE BLOOD, serum sodium, serum sodium level test, Measurement of sodium in serum, Serum sodium (& level) (procedure), Serum sodium (& level), Sodium - serum, Serum Sodium Ion Test, Serum sodium, Sodium measurement, serum, Serum sodium level, Sodium measurement, serum (procedure), Serum sodium measurement, ASSAY OF SERUM SODIUM, Assay of serum sodium, Serum sodium each test, serum sodium ea.tst
Dutch serum natrium
French Sodium sérique
German Natrium im Serum
Italian Sodio sierico
Portuguese Sódio sérico
Spanish Sodio en suero, Sodio; serico, medición de sodio en suero (procedimiento), medición de sodio en suero
Japanese 血清ナトリウム, ケッセイナトリウム
Czech Sodík v séru
Hungarian Szérum nátrium