Table 1 Commonly used equations for estimating 24-h urinary Na excretion from the spot urine sample
From: Monitoring population salt intake using casual urinary sodium: Tehran Lipid and Glucose Study
Name of equation | Description | History |
|---|---|---|
Kawasaki (1993) [29] | Male = 23 × 16.3 × [0.1 × (15.12 × Weight + 7.39 × Height − 12.63 × Age − 79.9) × Spot Na ÷ Spot Cr]0.5 Female = 23 × 16.3 × [0.1 × (8.58 × Weight + 5.09 × Height—4.72 × Age − 74.5) × Spot Na ÷ Spot Cr]0.5 | Initially developed among a Japanese population (159 healthy, free-living 20–79 y adults, using second morning voiding urine specimens and 24-h urine sampling (for 3–5 days) |
Tanaka (2002) [30] | Both genders = 23 × 21.98 × (0.1 × [- 2.04 × Age + 14.89 × Weight + 16.14 × Height − 2244.45] × Spot Na ÷ Spot Cr)0.392 | Initially developed among a Japanese population (591 adults, 20–59 y) using casual urine specimens and 24-h urine sampling |
Intersalt (2013) [31] | Male = 23 × (25.46 + 0.46 × Spot Na—2.75 × Spot Cr − 0.13 × Spot K + 4.10 × BMI + 0.26 × Age) Female = 23 × (5.07 + 0.34 × Spot Na—2.16 × Spot Cr − 0.09 × Spot K + 2.39 × BMI + 2.35 × Age − 0.03 × Age2) | Developed among the North American and European populations (5693 adults aged 20–59 y) |
Toft (2014) [32] | Male = 33.56 × [Spot Na ÷ Spot Cr × (− 7.54 × age + 14.15 × weight + 3.48 × height + 423.15]0.345 Female = 52.65 × [Spot Na ÷ Spot Cr × (− 6.13 age + 9.97 × weight + 1.24 × height + 342.73] 0.196 | Developed among Danish individuals (473) using 24-h urine collection and a spot urine sampling |
Whitton (2016) [20] | Both genders (for morning sample) = 23 × (88.66 + 0.55 × Spot Na—1.34 × Spot Cr—1.05 × Spot K − 0.87 × Age + 2.10 × BMI + 39.30 × Sex (male = 1, female = 0) + Ethnicity†(Malay = − 17.70, Indian = − 10.38, Chinese = 0) | Developed among Singaporean or permanent residents of Singapore (144 subjects, aged 18–79 y) using multiple spot urine sampling (morning, afternoon, evening) and a 24-h urine sampling |