title: Estimation of 24-hour urinary sodium excretion using spot urine samples.
abstract: The present study evaluated the reliability of equations using spot urine (SU) samples in the estimation of 24-hour urine sodium excretion (24-HUNa). Equations estimating 24-HUNa from SU samples were derived from first-morning SU of 101 participants (52.4 ± 11.1 years, range 24-70 years). Equations developed by us and other investigators were validated with SU samples from a separate group of participants (n = 224, 51.0 ± 10.9 years, range 24-70 years). Linear, quadratic, and cubic equations were derived from first-morning SU samples because these samples had a sodium/creatinine ratio having the highest correlation coefficient for 24-HUNa/creatinine ratio (r = 0.728, p < 0.001). In the validation group, the estimated 24-HUNa showed significant correlations with measured 24-HUNa values. The estimated 24-HUNa by the linear, quadratic, and cubic equations developed from our study were not significantly different from measured 24-HUNa, while estimated 24-HUNa by previously developed equations were significantly different from measured 24-HUNa values. The limits of agreement between measured and estimated 24-HUNa by six equations exceeded 100 mmol/24-hour in the Bland-Altman analysis. All equations showed a tendency of under- or over-estimation of 24-HUNa, depending on the level of measured 24-HUNa. Estimation of 24-HUNa from single SU by equations as tested in the present study was found to be inadequate for the estimation of an individual's 24-HUNa.
authors: Cardiovascular Center, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang-si, Gyeonggi 410-773, Korea. mooyong_rhee@dumc.or.kr.
authors: Moo-Yong
authors: MY
authors: Rhee
authors: Cardiovascular Center, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang-si, Gyeonggi 410-773, Korea. mdangela79@gmail.com.
authors: Ji-Hyun
authors: JH
authors: Kim
authors: Division of Nephrology, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang-si, Gyeonggi 410-773, Korea. shine@dumc.or.kr.
authors: Sung-Joon
authors: SJ
authors: Shin
authors: Clinical Trial Center, Dongguk University Ilsan Hospital, 27 Dongguk-ro, Ilsandong-gu, Goyang-si, Gyeonggi 410-773, Korea. namyi.gu@gmail.com.
authors: Namyi
authors: N
authors: Gu
authors: Cardiovascular Center, Dongguk University Gyeongju Hospital, 87 Dongdae-ro, Seokjang-dong, Gyeongju-si, Gyeongbuk 780-350, Korea. ptca@dongguk.ac.kr.
authors: Deuk-Young
authors: DY
authors: Nah
authors: Department of Cardiology, Hallym University College of Medicine, 77 Sakju-ro, Chuncheon-si, Gangwon-do 200-704, Korea. kshong@hallym.ac.kr.
authors: Kyung-Soon
authors: KS
authors: Hong
authors: Department of Cardiology, The Catholic University of Korea College of Medicine, 222 Banpodae-ro, Seocho-gu, Seoul 137-701, Korea. choej4oct@gmail.com.
authors: Eun-Joo
authors: EJ
authors: Cho
authors: Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, 29 Saemunan-ro, Jongro-Ku, Seoul 110-746, Korea. kcmd.sung@samsung.com.
authors: Ki-Chul
authors: KC
authors: Sung
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012964:Sodium / Q000378:metabolism / Q000652:urine*; D059349:Urine Specimen Collection / Q000379:methods*
chemical_list: D012964:Sodium