Table 3.

Recent studies on circadian variations in 24-h urinary sodium excretion^a

First author (reference)	Participant characteristics					Urinary sodium excretion
	N	M%	Age (y)	Race- ethnicity	Health characteristics	Time periods	Measure (unit)	Ratio	Pattern
Bankir (9)	141	64	18–40	29% B, 71% W	Healthy: BMI 18–39, Ccr ≥ 65 ml per min per 1.73 m2, difference in Cr excretion ≤50%, normotensive (not taking anti-HTN med) except 5 (3.5%)	06:00–22:00, 22:00–06:00	24 h (134–159 mmol) to nighttime (ND)	2.2–4.0	Lower at night
Mill (108)	109	46	30–74	Brazilian	Healthy, 37.6% HTN: nonpregnant, without self-reported heart or kidney disease	0:700–21:00, 21:00–07:00	Day (122 mmol) to night (104 mmol)	1.2	Similar day and night
Bankir (8)	325	45	46b	100% B, East African descent	Family history of HTN: participants from 73 families with ≥1 siblings with HTN, urinary Cr excretion ≤0.4 mmol/kg, usual diet	Day and night	Day (ND) to night (ND) (micromoles per minute)	0.9	Similar day and night
Fukuda (44)	65	51	16–80	100% A, Japanese	CKD: GFR <60 w/o diabetic nephropathy or nephrotic syndrome. Not taking anti-HTN medication or diuretics, classified by Ccr into tertilesc	06:00–21:00, 21:00–06:00	Day (78 mmol) to night (76 mmol)	1.0d	Similar day and nighte
Agarwal (3)	22	82	18–80	59% B, 41% W	CKD: GFR <60 or proteinuria of ≥1 g/d, nondialysis, ACE inhibitors and ARB constant dose ≥3 months before enrollment	Day and night	Day (6.7 mmol/h) to night (9.3 mmol/h)	0.7	Higher at night
Fukuda (45)	27	44	20–80	100% A, Japanese	CKD: GFR <60/kidney damage for 3+ months, including patients with nephropathy or nephritis but w/o diabetic nephropathy or taking anti-HTN medication or diuretics, classified by Ccr into tertilesf	06:00–21:00, 21:00–06:00	Day (4.2 mmol/h) to night (4.1 mmol/h)	1.0	Similar day and nightg
Fukuda (46)	26	57	17–72	100% A, Japanese	Glomerulopathy: diagnosed with renal biopsy. Classified by Ccr into tertilesh	06:00–21:00, 21:00–06:00	Day (6.7 mmol/h) to night (3.6 mmol/h)	1.4i	Lower at nightj

^aAbbreviations: A, Asian; ACE, angiotensin converting enzyme; ARB, angiotensin receptor blocker; B, black race; BMI, body mass index in kg/m²; C_cr, creatinine clearance in mL/min; GFR, glomerular filtration rate in ml/min/m²; HTN, hypertension; M, male; N, number of participants; ND, not reported; W, white race.

^bAverage age; range not reported (8).

^cTertile 1, C_cr 91–164 mL/min; tertile 2, C_cr 50–90 mL/min; tertile 3, C_cr 5–41 mL/min (44).

^dAverage night:day ratio in urine sodium excretion rate (mmol/h) was reported as 1.05 (44).

^eAverage night:day ratios in urinary sodium excretion rates (mmol/h) were 0.59 for tertile 1 of creatinine clearance (highest), 0.86 for tertile 2, and 1.69 for tertile 3 (lowest) (44).

^fGroup A, C_cr > 90 mL/min; Group B, C_cr 30–89 mL/min; Group C, C_cr < 29 mL/min (45).

^gNocturnal reduction in urinary sodium excretion rates (mmol/h) significantly different (P < 0.001) by level of creatinine clearance. Nocturnal reduction is highest in the group with the highest creatinine clearance and lowest in the group with the lowest creatinine clearance (45).

^hLower C_cr 16–62 mL/min; medium C_cr 75–92 mL/min; higher C_cr 106–15 1 mL/min (46).

ⁱIn the paper, the night:day ratio for the overall group is 0.75, which is different from that calculated from the average day:night ratio (46).

^jNocturnal reduction in urinary sodium excretion rates (mmol/h) significantly different (P <0.012) by level of creatinine clearance. Nocturnal reduction is highest in the group with the highest creatinine clearance (night:day ratio 0.44) and was flat (night:day ratio 0.99) in the group with the lowest creatinine clearance (46).