Appropriate use of spot-urine sodium estimates for population-level and exploratory analyses: a response to Campbell and Cappuccio

Jonas Wuopio; Lin Yi-Ting; Koen F Dekkers; Tove Fall; J Gustav Smith; Anders Larsson; Gunnar Engström; Marju Orho-Melander; Linda Johnson; Johan Ärnlöv

doi:10.1186/s12986-025-01056-2

Appropriate use of spot-urine sodium estimates for population-level and exploratory analyses: a response to Campbell and Cappuccio

Nutr Metab (Lond). 2026 Feb 5;23(1):18. doi: 10.1186/s12986-025-01056-2.

Authors

Jonas Wuopio^{1

2}, Lin Yi-Ting^{3

4}, Koen F Dekkers⁵, Tove Fall⁵, J Gustav Smith^{6

7

8}, Anders Larsson⁹, Gunnar Engström¹⁰, Marju Orho-Melander¹⁰, Linda Johnson^{10

11}, Johan Ärnlöv^{3

12

13}

Affiliations

¹ Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden. jonas.wuopio@ki.se.
² Center for clinical research, Uppsala University Region Dalarna, Falun, Sweden. jonas.wuopio@ki.se.
³ Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden.
⁴ Department of Family Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
⁵ Molecular Epidemiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
⁶ The Wallenberg Laboratory/Department of Molecular and Clinical Medicine, Institute of Medicine, Gothenburg University and the Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
⁷ Department of Cardiology, Clinical Sciences, Lund University and Skåne University Hospital, Lund, Sweden.
⁸ Wallenberg Center for Molecular Medicine and Lund University Diabetes Center, Lund University, Lund, Sweden.
⁹ Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden.
¹⁰ Department of Clinical Sciences in Malmö, Lund University, Malmö, Sweden.
¹¹ Population Health Research Institute, McMaster University, Ontario, Canada.
¹² Center for clinical research, Uppsala University Region Dalarna, Falun, Sweden.
¹³ School of Health and Social Studies, Dalarna University, Falun, Sweden.

Abstract

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.

Publication types

Letter