スポット尿中ナトリウム推定値の集団レベルおよび探索的分析における適切な使用：CampbellおよびCappuccioへの応答

In response to Campbell and Cappuccio's comments, this letter clarifies and defends the appropriate use of spot-urine sodium estimates in population-level and exploratory analyses. The critique misrepresents key aspects of the study design and overstates the limitations of spot-urine equations. While acknowledging that these methods are unsuitable for precise individual assessment, they perform adequately for ranking individuals and examining population-level associations, as supported by extensive validation studies. The reported associations with metabolic traits were internally consistent, biologically plausible, and in agreement with findings from studies using 24-hour urine collections. Dismissing such analyses as "invalid" undermines constructive scientific dialogue and disregards the exploratory value of transparent, hypothesis-generating research.