. 2013 Jun 12;143(8):1276–1282. doi: 10.3945/jn.113.175927

TABLE 4.

Mean urine volume and concentration of sodium, potassium, chloride, creatinine, and iodine in timed-spot urine specimens in the d 1 collection by race and gender¹ ²

	Timing of spot urine collection
	Morning	Afternoon	Evening	Overnight
Total volume, mL
Black male	184 ± 111^a	173 ± 81^a	184 ± 81^a	257 ± 123^b
Black female	168 ± 108^a	178 ± 91^a	182 ± 104^a	271 ± 178^b
Other male	206 ± 148^a	233 ± 139^a*	212 ± 100^a*	321 ± 163^b*
Other female	159 ± 111^a†	220 ± 125^b*	199 ± 114^b	288 ± 134^c
Sodium, mmol/L
Black male	141 ± 62^a	146 ± 69^a	139 ± 74^a,b	121 ± 69^b
Black female	145 ± 64^a	148 ± 72^a	136 ± 75^a,b	121 ± 54^b
Other male	123 ± 61^a	117 ± 64^a,b*	129 ± 66^a	102 ± 57^b*
Other female	118 ± 58^a*	104 ± 62^a,b*	115 ± 63^a*	97 ± 52^b*
Potassium, mmol/L
Black male	58 ± 35^a	58 ± 35^a	45 ± 31^b	35 ± 23^c
Black female	55 ± 31^a,b	56 ± 33^a	48 ± 32^b	32 ± 18^c
Other male	64 ± 35^a	59 ± 33^a	56 ± 35^a*	36 ± 26^b
Other female	56 ± 33^a	54 ± 38^a	55 ± 35^a	30 ± 19^b
Chloride, mmol/L
Black male	150 ± 71^a,b	152 ± 76^a	131 ± 70^b	105 ± 62^c
Black female	150 ± 65^a,b	155 ± 72^a	133 ± 74^b	105 ± 51^c
Other male	144 ± 72^a	132 ± 73^a,b	130 ± 67^b	85 ± 55^c*
Other female	128 ± 66^a*	121 ± 67^a*	118 ± 66^a	77 ± 45^b*
Creatinine, mmol/L
Black male	17 ± 9	18 ± 9	17 ± 10	18 ± 9
Black female	14 ± 8^†	14 ± 7^†	15 ± 9	14 ± 7^†
Other male	15 ± 9*	14 ± 8*	15 ± 9	15 ± 8³
Other female	12 ± 8^a	9 ± 6^b*^†	10 ± 6^a*^†	12 ± 7^a†
Iodine, μg/L
Black male	198 ± 160	224 ± 292	201 ± 205	238 ± 296
Black female	196 ± 185	216 ± 284	206 ± 301	200 ± 219
Other male	242 ± 272	217 ± 227	227 ± 208	261 ± 325
Other female	205 ± 160	177 ± 157	229 ± 227	242 ± 346

Values are means ± SDs. Within an analyte, labeled means in a row without a common letter differ, P < 0.05 (with Bonferroni adjustment). *Within an analyte, different from blacks within the same gender using the same timed-spot specimens, P < 0.05. ^†Within an analyte, different from males within the same race category using the same timed-spot specimens, P < 0.05.

Timing of specimens: morning (the second void upon rising in the morning), 0830 to 1230 h; afternoon, 1231 to 1730 h; evening, 1731 to 2359 h; overnight (the first void after the longest period of sleep), 0400–1200 h the next morning. See Supplemental Table 5 for number of observations in each cell.