Can methods based on spot urine samples be used to estimate average population 24 h sodium excretion? Results from the Isfahan Salt Study

Noushin Mohammadifard, Hamidreza Marateb, Marjan Mansourian, Alireza Khosravi, Zahra Abdollahi, Norman R.C. Campbell, Jacqui Webster, Kristina Petersen, Nizal Sarrafzadegan

Research output: Contribution to journalArticle

Abstract

Objective: To assess agreement between established methods of estimating salt intake from spot urine collections and 24 h urinary Na (24hUNa) and then to develop a valid formula that can be used in the Iranian population to estimate salt intake from spot urine samples.Design: A validation study. Three spot urine samples were collected (fasting second-void morning; afternoon; evening) on the same day as a 24 h urine collection. We estimated 24hUNa from spot specimens using the Kawasaki, Tanaka and INTERSALT equations. Two new formulas were developed, the Iran formula 1 (Iran 1) and Iran formula 2 (Iran 2), based on our population characteristics.Setting: Iranian adults recruited in 2014-2015.Participants: Healthy volunteer adults aged ≥18 years.Results: With all three spot urine specimens, predicted population 24hUNa was underestimated based on the INTERSALT equation (-469 to -708 mg/d; all P < 0·05) and conversely overestimation occurred with the Kawasaki equation (926 to 1080 mg/d; all P < 0·01). The Tanaka equation produced comparable estimates to measured 24hUNa (-151 to 86 mg/d; all P > 0·49). The newly derived formulas, Iran 1 and Iran 2, showed less mean bias than the established equations (Iran 1: 43 to 80 mg/d, all P > 0·55; Iran 2: 22 to 90 mg/d, all P > 0·50).Conclusions: In this Iranian sample, the Tanaka equation and newly derived formulas produced group-level estimates comparable to measured 24hUNa. The newly developed formulas showed less mean bias than established equations; however, they need to be tested for generalization in a larger sample.

Original languageEnglish (US)
Pages (from-to)202-213
Number of pages12
JournalPublic Health Nutrition
Volume23
Issue number2
DOIs
Publication statusPublished - Feb 1 2020

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All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health

Cite this

Mohammadifard, N., Marateb, H., Mansourian, M., Khosravi, A., Abdollahi, Z., Campbell, N. R. C., ... Sarrafzadegan, N. (2020). Can methods based on spot urine samples be used to estimate average population 24 h sodium excretion? Results from the Isfahan Salt Study. Public Health Nutrition, 23(2), 202-213. https://doi.org/10.1017/S136898001900257X