Lab

Serum Sodium

search

Serum Sodium, Serum Na, Corrected Serum Sodium for Glucose, Corrected Serum Sodium for Hyperglycemia

  • See Also
  1. Sodium and Water Homeostasis
  2. Hyponatremia
  3. Hypernatremia
  4. Total Body Sodium Deficit (Includes Total Body Water and Free Water Deficit Calculations)
  5. Serum Osmolality
  6. Osmolal Gap
  7. Urine Sodium
  8. Fractional Excretion of Sodium (FENa)
  • Physiology
  • Sodium homeostasis
  1. See Sodium and Water Homeostasis
  • Interpretation
  • General
  1. Normal: 135-145 mEq/L
  2. Abnormal
    1. Hypernatremia
      1. Serum Sodium over 145
    2. Hyponatremia
      1. Serum Sodium under 135
  • 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]
  • Resources
  1. MDCalc Corrected Serum Sodium
    1. http://www.mdcalc.com/sodium-correction-for-hyperglycemia/
  • References
  1. Braun (2015) Am Fam Physician 91(5): 299-307 [PubMed]