What are the correction factors for the effect of plasma lipids on plasma Na+ concentration?

Updated: Aug 16, 2019
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Extreme elevations in plasma lipids or proteins can increase the plasma volume and can reduce the measured plasma Na+ concentration. Na+ is contained in the aqueous phase of plasma; the proteins and lipids cause an increase in the nonaqueous phase of plasma, leading to an overall increase in plasma volume without an actual decrease or dilution of Na+ in the aqueous phase. This was more of an issue in the past in the United States, when the conventional method of measuring Na+ (ie, flame-emission spectrophotometry) measured the aqueous and nonaqueous phases of plasma. The correction factors are as follows:

  • Plasma triglycerides (g/L) x 0.002 = mEq/L decrease in Na+

  • Plasma protein level - 8 (g/L) x 0.025 = mEq/L decrease in Na+


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