J Korean Med Sci.  2014 Sep;29(Suppl 2):S97-S102. 10.3346/jkms.2014.29.S2.S97.

Estimating 24-Hour Urine Sodium Level with Spot Urine Sodium and Creatinine

• Koo HS
• Kim YC
• Ahn SY
• Oh SW
• Kim S
• Chin HJ
• Park JH

• KMID: 2069799
• DOI: http://doi.org/10.3346/jkms.2014.29.S2.S97

Abstract

The 24-hr urine sodium excretion level was estimated based on the spot urine sodium, and the efficacy of the formula was validated to determine the status of low salt intake <100 mEq Na/day. The 24-hr urine samples were collected from 400 patients. The 24-hr urine creatinine level was estimated with the use of three formulas: a newly derived Korean equation (E24UCR_K), and Tanaka (E24UCR_T) and Cockcroft-Gault (E24UCR_CG) equations. The correlation coefficients between the estimated and measured 24-hr urine creatinine for these three equations were 0.863, 0.846, and 0.896, respectively (All P<0.001). After estimating the 24-hr urine sodium levels, the correlation coefficients between the estimated and measured 24-hr urine sodium levels were 0.466, 0.490, and 0.516, respectively (All P<0.001). The sensitivity of three formulas to estimate the measured 24-hr urine sodium> or =100 mEq/day using the estimated amount> or =100 mEq/day was 84.3%, 87.6%, and 84.8%, respectively. In conclusion, the three equations used to estimate the 24-hr urine sodium content were useful to determine the status of low salt intake.

Keyword

24-hr Urine Sodium; Spot Urine Sodium; Spot Urine Creatinine

MeSH Terms

Adult
Aged
Algorithms
Area Under Curve
Creatinine/*urine
Demography
Female
Glomerular Filtration Rate
Humans
Male
Middle Aged
ROC Curve
Sodium, Dietary/*urine
Urine Specimen Collection
Creatinine
Sodium, Dietary

Figure

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  Fig. 1 Correlation between creatinine excretion estimated in spot urine samples and creatinine excretion assessed in 24-hr urine samples.

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  Fig. 2 Correlation between sodium excretion estimated in spot urine samples and sodium excretion assessed in 24-hr urine samples.

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  Fig. 3 Bland-Altman plot for the difference between the measured and estimated sodium excretion levels.

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  Fig. 4 Area under the ROC curve for predicting the 24-hr urine sodium level in patients whose sodium level was more than 100 mEq/L.

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