The relationship between repeated measurement of casual and 24-h urinary sodium-to-potassium ratio in patients with chronic kidney disease

Yuka Okuyama, Haruhito Adam Uchida, Toshiyuki Iwahori, Hiroyoshi Segawa, Ayako Kato, Hidemi Takeuchi, Yuki Kakio, Ryoko Umebayashi, Masashi Kitagawa, Hitoshi Sugiyama, Katsuyuki Miura, Hirotsugu Ueshima, Jun Wada

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1 Citation (Scopus)

Abstract

This study aimed to clarify the relationship between repeated measurements of casual (spot) and 24-h urinary sodium-to-potassium (Na/K) ratios in patients with chronic kidney disease (CKD). A total of 61 inpatients with CKD, 31 in stage 1–3 (eGFR [estimated glomerular filtration rate] ≥ 30 ml/min/1.73 m2) and 30 in stage 4–5 (eGFR < 30 ml/min/1.73 m2), aged 20–85 consuming a low-sodium diet (NaCl [sodium chloride] 6 g/day) were recruited. Urinary Na, K, and Na/K ratios were measured in both casual urine samples and 2-day, 24 h urine samples, and then analyzed by correlation and Bland–Altman analyses. Mean 24-h urine Na/K ratio was higher in participants in stage 4–5 (5.1) than in participants in stage 1–3 (4.1) CKD. Casual urine Na/K ratio was strongly correlated with 2-day, 24-h urine Na/K ratio by sampling 4 casual urine specimens every morning and evening in participants in stage 1–3 (r = 0.69–0.78), but not in stage 4–5 (r = 0.12–0.19). The bias for mean Na/K ratio between 2-day, 24-h urine, and the 4 casual urine sampling ranged from −0.86 to 0.16 in participants in stage 1–3, and the quality of agreement for the mean of this casual urine sampling was similar to that of sampling 8 casual urine samples for estimating 2-day, 24-h values. Methods using repeated casual urine Na/K ratios may provide a reasonable estimation of 24-h urine Na/K ratio in normotensive and hypertensive as well as individuals with stage 1–3, but not stage 4–5 CKD.

Original languageEnglish
JournalJournal of Human Hypertension
DOIs
Publication statusAccepted/In press - Jan 1 2018

ASJC Scopus subject areas

  • Internal Medicine

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