Dataset Information

Can spot urine measurement be a substitute for 24-hour urine measurement to estimate sodium intake in adolescents?

ABSTRACT:

Importance

Several methods have been established in recent decades that allow use of spot urine to estimate dietary sodium intake. However, their accuracies have been controversial in children.

Objective

To validate the performance of three commonly used methods-the Kawasaki, Tanaka, and International Cooperative Study on Salt, Other Factors, and Blood Pressure (INTERSALT) methods. Additionally, this study explored the accuracies of the Tanaka and INTERSALT methods by using spot urine samples taken at four separate times.

Method

Forty-one adolescents aged 14 to 16 years completed two non-consecutive 24-hour urine collections and their mean values were used as reference data. The second-morning urine was used for assessment with the Kawasaki method; a casual spot urine and spot urine samples taken at four separate times (morning, afternoon, evening, and overnight) were used for assessment with the Tanaka and INTERSALT methods.

Results

The mean differences were 1801 mg, 542 mg, 47 mg, and -31 mg for the Kawasaki, Tanaka, INTERSALT1 (with potassium), and INTERSALT2 (without potassium) methods with their required spot urine, respectively. The proportions of relative difference levels within ± 10% were 4.9% for the Kawasaki method, 19.5% for the Tanaka method, 36.6% for the INTERSALT1 method, and 36.6% for the INTERSALT2 method.

Interpretation

The INTERSALT method seemed to provide minimally biased estimations of mean population sodium intake with casual spot urine. However, there is a need to be cautious regarding inconsistencies in estimation among different levels of sodium intake. The methods assessed in this study were unable to accurately estimate sodium intake at the individual level.

SUBMITTER: Dong J

PROVIDER: S-EPMC7984014 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Sodium intake influences blood pressure and proteinuria, yet the impact on long-term outcomes is uncertain in chronic kidney disease (CKD). Accurate assessment is essential for clinical and public policy recommendations, but few large-scale studies use 24-h urine collections. Recent studies that used spot urine sodium and associated estimating equations suggest that they may provide a suitable alternative, but their accuracy in patients with CKD is unknown.We compared the accuracy of 4 equations [the Nerbass, INTERSALT (International Cooperative Study on Salt, Other Factors, and Blood Pressure), Tanaka, and Kawasaki equations] that use spot urine sodium to estimate 24-h sodium excretion in patients with moderate to advanced CKD.We evaluated the accuracy of spot urine sodium to predict mean 24-h urine sodium excretion over 9 mo in 129 participants with stage 3-4 CKD. Spot morning urine sodium was used in 4 estimating equations. Bias, precision, and accuracy were assessed and compared across each equation.The mean age of the participants was 67 y, 52% were female, and the mean estimated glomerular filtration rate was 31 ± 9 mL · min(-1) · 1.73 m(-2) The mean ± SD number of 24-h urine collections was 3.5 ± 0.8/participant, and the mean 24-h sodium excretion was 168.2 ± 67.5 mmol/d. Although the Tanaka equation demonstrated the least bias (mean: -8.2 mmol/d), all 4 equations had poor precision and accuracy. The INTERSALT equation demonstrated the highest accuracy but derived an estimate only within 30% of mean measured sodium excretion in only 57% of observations. Bland-Altman plots revealed systematic bias with the Nerbass, INTERSALT, and Tanaka equations, underestimating sodium excretion when intake was high.These findings do not support the use of spot urine specimens to estimate dietary sodium intake in patients with CKD and research studies enriched with patients with CKD. The parent data for this study come from a clinical trial that was registered at clinicaltrials.gov as NCT00785629.

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