An improved approach to report creatinine-corrected analyte concentrations in urine

Figures & data

Table 1. Un-weighted sample sizes by age, gender, race/ethnicity, and survey year. Data from National Health and Nutrition Examination Survey 2007–2014

	Survey year
	2007–2010		2011–2012		2013–2014		Total
	N	%	N	%	N	%	N	%
Total	16,179	100.0	7,581	100.0	8,052	100.0	31,812	100.0
Males	8,085	50.0	3,828	50.5	3,950	49.1	15,863	49.9
Females	8,064	49.8	3,753	49.5	4,102	50.9	15,919	50.0
Non-Hispanic Whites	6,896	42.6	2,449	32.3	3,004	37.3	12,349	38.8
Non-Hispanic Blacks	3,316	20.5	2,066	27.3	1,790	22.2	7,172	22.5
Hispanics	5,115	31.6	1,765	23.3	2,067	25.7	8,947	28.1
Other race/ethnicities	822	5.1	1,301	17.2	1,191	14.8	3,314	10.4
Age 6–11 years	2,368	14.6	1,235	16.3	1,236	15.4	4,839	15.2
Age 12–19 years	2,454	15.2	1,202	15.9	1,348	16.7	5,004	15.7
Age 20–29 years	1,774	11.0	906	12.0	903	11.2	3,583	11.3
Age 30–39 years	1,897	11.7	892	11.8	949	11.8	3,738	11.8
Age 40–49 years	1,970	12.2	858	11.3	990	12.3	3,818	12.0
Age 50–59 years	1,789	11.1	867	11.4	902	11.2	3,558	11.2
Age 60–69 years	1,866	11.5	850	11.2	897	11.1	3,613	11.4
Age ≥70 years	2,031	12.6	771	10.2	827	10.3	3,629	11.4

Table 2. Unweighted sample sizes for urinary 3-phenoxybenzoic acid for 2009–2010, urinary cadmium (UCD) and lead (UPB) for 2013–2014, and urinary perchlorate (UP8), nitrate (UNO3), and thiocyanate (USCN) for 2011–2012 by gender, race/ethnicity, and age. Data from National Health and Nutrition Examination Survey 2009–2010

	3-Phonoxybenzoic acid		UCD, UPB		UP8, UNO3, USCN
	N	%	N	%	N	%
Total	2,703	100.0	2,681	100.0	2,506	100
Males	1,331	49.2	1,319	49.2	1,264	50.4
Females	1,372	50.8	1,362	50.8	1,242	49.6
Non-Hispanic Whites	1,188	44.0	952	35.5	820	32.7
Non-Hispanic Blacks	492	18.2	586	21.9	672	26.8
Hispanics	877	32.4	705	26.3	571	22.8
Others	146	5.4	398	14.8	443	17.7
Age: 6–11 years	383	14.2	405	15.1	401	16.0
Age: 12–19 years	398	14.7	454	16.9	393	15.7
Age: 20–64 years	1,449	53.6	1,428	53.3	1,338	53.4
Age: 65+ years	473	17.5	394	14.7	374	14.9

Table 3. Un-adjusted means and geometric means with 95% confidence intervals in mg/dL for urine creatinine by age, gender, and race/ethnicity for 2007–2010. Data from National Health and Nutrition Examination Survey 2007–2010

	Mean (95% CI)*	Geometric mean (95% CI)**
Males (M)	137.4 (133.7–141.2)	114 (110.6–117.6)
Females (F)	106.1 (103.3–108.8)	82.3 (79.9–84.8)
Non-Hispanic Whites (NHW)	115.3 (112.1–118.5)	91.5 (88.6–94.5)
Non-Hispanic Blacks (NHB)	160.3 (156.4–164.1)	132.6 (129–136.2)
Hispanics (HISP)	124.1 (120.6–127.6)	101.2 (98.2–104.2)
Other race/ethnicities (OTH)	109 (103.2–114.8)	86 (81.1–91.1)
Age 6–11 years (A6)	92 (89.3–94.7)	77.1 (74.4–79.9)
Age 12–19 years (A12)	147.2 (141.6–152.7)	122 (116.6–127.7)
Age 20–29 years (A20)	148.5 (142.5–154.4)	119.7 (113.7–126)
Age 30–39 years (A30)	129.5 (125.1–133.9)	104 (99.4–108.8)
Age 40–49 years (A40)	122.5 (118.1–127)	97.7 (93.8–101.8)
Age 50–59 years (A50)	110.7 (106.8–114.6)	86 (82.2–90.1)
Age 60–69 years (A60)	101.6 (97.2–106.1)	81.2 (77.4–85.3)
Age ≥ 70 years (A70)	97.6 (95–100.3)	79.8 (77.4–82.4)

* M > F (p < 0.01), NHB > HISP > NHW > OTH (p ≤ 0.03), all pairwise differences among age groups were statistically significantly different at p ≤ 0.02 except those between A20 and A30 and between A60 and A70.

** M > F (p < 0.01), NHB > HISP > NHW > OTH (p ≤ 0.04), all pairwise differences among age groups were statistically significantly different at p ≤ 0.02 except those between A6 and A60, A6 and A70, A20 and A30 and between A60 and A70.

Table 4. Slopes and standard errors of slopes by combinations of age, gender, and race/ethnicity (CATS_G_R_A) for the model fitted for log 10 transformed values of urine creatinine with CATS_G_R_A and body mass index used as independent variables in the model*. Data from National Health and Nutrition Examination Survey 2007–2010

Row	Gender	Race/ethnicity	Age in years	Slope	Standard error
1	Male	Non-Hispanic White	6–12	0.148096	0.0605576
2			12–19	0.315778	0.0553185
3			20–29	0.294669	0.0568377
4			30–39	0.200626	0.0574311
5			40–49	0.208201	0.057859
6			50–59	0.178453	0.0530254
7			60–69	0.143568	0.0525619
8			≥70	0.135787	0.0550916
9		Non-Hispanic Black	6–12	0.221922	0.0566471
10			12–19	0.399809	0.0591483
11			20–29	0.430921	0.0557101
12			30–39	0.386519	0.0589081
13			40–49	0.30341	0.0597381
14			50–59	0.303954	0.0605754
15			60–69	0.265808	0.0581445
16			≥70	0.268518	0.065233005
17		Hispanic	6–12	0.129248	0.057357
18			12–19	0.277913	0.0554802
19			20–29	0.269241	0.0518996
20			30–39	0.244965	0.0570431
21			40–49	0.24595	0.052828
22			50–59	0.214864	0.0541762
23			60–69	0.157343	0.0520925
24			≥70	0.176694	0.0590139
25		Other race/ethnicity	6–12	0.118987	0.0831046
26			12–19	0.253322	0.0617044
27			20–29	0.213729	0.0607875
28			30–39	0.234844	0.0552653
29			40–49	0.187221	0.064117693
30			50–59	0.233232	0.0609498
31			60–69	0.142311	0.072895093
32			≥70	0.212541	0.062668111
33	Female	Non-Hispanic White	6–12	0.088864	0.0517534
34			12–19	0.219043	0.0587706
35			20–29	0.160863	0.0572401
36			30–39	0.078432	0.063614285
37			40–49	0.045087	0.0573441
38			50–59	−0.04519	0.0534013
39			60–69	−0.03239	0.0566947
40			≥70	−0.00956	0.0547967
41		Non-Hispanic Black	6–12	0.125388	0.0621399
42			12–19	0.330725	0.0614309
43			20–29	0.352766	0.053506
44			30–39	0.254497	0.05949
45			40–49	0.217059	0.0561932
46			50–59	0.172472	0.065020643
47			60–69	0.111914	0.060535
48			≥70	0.096324	0.0586921
49		Hispanic	6–12	0.054322	0.0586872
50			12–19	0.24098	0.0520909
51			20–29	0.168985	0.059269
52			30–39	0.142251	0.0538136
53			40–49	0.053249	0.0593633
54			50–59	0.048277	0.0624553
55			60–69	−0.00275	0.0607953
56			≥70	−0.04502	0.065866793
57		Other race/ethnicities	6–12	0.03117	0.062504891
58			12–19	0.218774	0.078029721
59			20–29	0.152808	0.092518613
60			30–39	0.053096	0.083483762
61			40–49	0.058179	0.0594316
62			50–59	−0.10556	0.068935688
63			60–69	−0.21646	0.080355112
64			≥70	0	0

* N used in the model was 15,997, R² was 15.4%, and slope for body mass index was 0.0073716.

Table 5. Model effect statistics when regression models were fitted for log 10 transformed values of urine creatinine in mg/dL uncorrected and corrected for the effect of age, gender, race/ethnicity, and body mass index for the levels of urine creatinine. Data from National Health and Nutrition Examination Survey 2007–2010

		Uncorrected model		Corrected model
		F	p	F	p
Cats 64, body mass index	Model	448.4	<0.01	33.6	<0.01
	Intercept	22899.5	<0.01	18174.6	<0.01
	Cats	186.6	<0.01	1.5	0.13
	Body mass index	375.1	<0.01	387.2	<0.01
	N	15997		15997
	R^2	15.4%		3.0%
Age, gender, race/ethnicity, body mass index	Model	290.1	<0.01	74.2	<0.01
	Intercept	22071.2	<0.01	18243.7	<0.01
	Gender	606.9	<0.01	0.0	0.99
	Race/ethnicity	129.7	<0.01	0.0	0.99
	Age	119.1	<0.01	0.1	1.00
	Body mass index	383.3	<0.01	383.0	<0.01
	N	15997		15997
	R^2	14.4%		3.0%

Table 6. Model effect statistics when regression models were fitted for log 10 transformed values of urine creatinine in mg/dL corrected for the effect of age, gender, race/ethnicity, and body mass index for the levels of urine creatinine. Data from National Health and Nutrition Examination Survey 2011–2014

		Survey year
		2011–2012		2013–2014
		F	p	F	p
Age, gender, race/ethnicity, body mass index	Model	78.03050541	<0.01	114.7671801	<0.01
	Intercept	5,048.981344	<0.01	3,579.002001	<0.01
	Gender	0.187158739	0.67	0.216593718	0.65
	Race/ethnicity	2.652692216	0.08	2.444985999	0.10
	Age	3.612729443	0.01**	4.05724393	0.01*
	Body Mass Index	125.6361483	<0.01	81.7091196	<0.01
	N	7,499		7,986
	R^2	5.3%		5.1%

* Statistically significant differences between those aged 20–29 years old and 30–39 years old (p = 0.01), 60–69 years old (p = 0.04) and ≥70 years old (p = 0.02); between those aged 30–39 and 60–69 years old (p = 0.01); and between those aged 60–69 and ≥70 years old (p = 0.03) were observed.

** Statistically significantly differences between those aged 12–19 and 60–69 years old (p = 0.02) and ≥70 years old and between those aged 30–39 and 60–69 years old (p = 0.03) were observed.

Table 7. Creatinine corrected and modified creatinine-corrected geometric means (GM) with 95% confidence intervals for 3-phenoxybenzoic acid by age, gender, and race/ethnicity. Data from National Health and Nutrition Examination Survey 2009–2010

	Creatinine corrected GM in ng/mg creatinine	Modified creatinine corrected GM in ng/mg creatinine
6–11 (A6)	0.744 (0.537–1.031)	0.986 (0.72–1.351)
12–19 (A12)	0.347 (0.302–0.399)	0.668 (0.585–0.762)
20–64 (A20+)	0.429 (0.401–0.46)	0.613 (0.572–0.658)
65+ (A65+)	0.42 (0.377–0.467)	0.477 (0.423–0.538)
Males (M)	0.377 (0.348–0.409)	0.636 (0.588–0.688)
Females (F)	0.507 (0.453–0.566)	0.612 (0.549–0.683)
Non-Hispanic White (NHW)	0.451 (0.416–0.488)	0.608 (0.565–0.655)
Non-Hispanic Black (NHB)	0.354 (0.282–0.444)	0.678 (0.542–0.847)
Hispanics (HISP)	0.414 (0.379–0.452)	0.62 (0.566–0.681)
Other race/ethnicities (OTH)	0.55 (0.415–0.73)	0.705 (0.523–0.951)
Statistically Significant Differences	A6 > A12 (p < 0.01), A6 > A20+ (p < 0.01), A6 > A65+ (p < 0.01), A12  <  A20+ (p < 0.01), A12  < A65+ (p = 0.04), M  <  F (p < 0.01), NHW > NHB (p = 0.03), NHB < OTH (p = 0.01), HISP < OTH (p = 0.047)	A6 > A12 (p = 0.01), A6 > A20+ (p < 0.01), A6 > A65+ (p < 0.01), A12 > A20+ (p < 0.01), A12 > A65+ (p < 0.01)

Table 8. Creatinine corrected and modified creatinine-corrected geometric means (GM) with 95% confidence intervals for urinary cadmium and lead by age, gender, and race/ethnicity. Data from National Health and Nutrition Examination Survey 2013–2014

Demographic group	Creatinine corrected GM in ng/mg creatinine	Modified creatinine corrected GM in ng/mg creatinine
Urine cadmium
Age: 6–11 years (A6)	0.054 (0.05–0.059)	0.071 (0.066–0.077)
Age: 12–19 years (A12)	0.058 (0.053–0.064)	0.11 (0.1–0.121)
Age: 20–64 years (A20+)	0.16 (0.153–0.169)	0.229 (0.215–0.243)
Age: 65+ years (A65+)	0.318 (0.281–0.358)	0.366 (0.328–0.409)
Males (M)	0.118 (0.108–0.128)	0.198 (0.183–0.214)
Females (F)	0.174 (0.162–0.186)	0.21 (0.195–0.226)
Non-Hispanic White (NHW)	0.15 (0.137–0.163)	0.201 (0.185–0.218)
Non-Hispanic Black (NHB)	0.136 (0.114–0.162)	0.256 (0.22–0.299)
Hispanics (HISP)	0.113 (0.1–0.127)	0.167 (0.151–0.186)
Other race/ethnicities (OTH)	0.183 (0.155–0.216)	0.24 (0.208–0.277)
Statistically significant differences	A6 < A20+ (p < 0.01), A6 < A65+ (p < 0.01), A12 < A20+ (p < 0.01), A12 < A65+ (p < 0.01), A20+ < A65+ (p < 0.01), M < F (p < 0.01), NHW > HISP (p < 0.01), NHW < OTH (p = 0.04), HISP < OTH (p < 0.01)	A6 < A12 < A20+ < A65+ (p < 0.01), NHW < NHB (p < 0.01), NHW > HISP (p < 0.01), NHW < OTH (p = 0.04), NHB <HISP (p < 0.01), HISP < OTH (p < 0.01)
Urine lead
Age: 6–11 years (A6)	0.331 (0.297–0.37)	0.436 (0.391–0.487)
Age: 12–19 years (A12)	0.182 (0.16–0.208)	0.345 (0.304–0.392)
Age: 20–64 years (A20+)	0.317 (0.3–0.336)	0.453 (0.424–0.484)
Age: 65+ Years (A65+)	0.513 (0.465–0.565)	0.591 (0.535–0.652)
Males (M)	0.315 (0.293–0.339)	0.531 (0.493–0.571)
Females (F)	0.325 (0.303–0.348)	0.392 (0.366–0.42)
Non-Hispanic White (NHW)	0.329 (0.306–0.353)	0.442 (0.411–0.476)
Non-Hispanic Black (NHB)	0.282 (0.251–0.317)	0.532 (0.48–0.589)
Hispanics (HISP)	0.301 (0.276–0.328)	0.446 (0.406–0.489)
Other race/ethnicities (OTH)	0.351 (0.311–0.396)	0.461 (0.408–0.52)
Statistically significant differences	A6 < A12 (p < 0.01), A6 < A65+ (p < 0.01), A12 < A20+ (p < 0.01), A12 < A65+ (p < 0.01), A20+ < A65+ (p < 0.01), NHW > NHB (p = 0.02), NHW > HISP (p = 0.02), NHB < OTH (p < 0.01), HSP < OTH (p < 0.01)	A6 > A12 (p < 0.01), A6 > A65+ (p < 0.01), A12 < A20+ (p < 0.01), A12 < A65+ (p < 0.01), A20+ < A65+ (p < 0.01), M > F (p < 0.01), NHW < NHB (p < 0.01), NHB > HISP (p < 0.01)

Table 9. Creatinine corrected and modified creatinine-corrected geometric means (GM) with 95% confidence intervals for urinary perchlorate, nitrate, and thiocyanate by age, gender, and race/ethnicity. Data from National Health and Nutrition Examination Survey 2011–2012

Demographic group	Creatinine corrected GM in ng/mg creatinine	Modified creatinine corrected GM in ng/mg creatinine
Urine perchlorate
Age: 6–11 years (A6)	5.559 (5.046–6.124)	7.274 (6.467–8.181)
Age: 12–19 years (A12)	2.699 (2.503–2.911)	5.205 (4.86–5.574)
Age: 20–64 years (A20+)	3.218 (2.998–3.455)	4.56 (4.325–4.808)
Age: 65+ years (A65+)	3.729 (3.178–4.374)	4.353 (3.745–5.06)
Males (M)	3.117 (2.839–3.423)	5.221 (4.809–5.669)
Females (F)	3.647 (3.417–3.892)	4.413 (4.17–4.671)
Non-Hispanic White (NHW)	3.578 (3.353–3.819)	4.793 (4.507–5.097)
Non-Hispanic Black (NHB)	2.277 (2.104–2.464)	4.297 (4.007–4.608)
Hispanics (HISP)	3.51 (2.938–4.192)	5.227 (4.372–6.248)
Other race/ethnicities (OTH)	3.593 (3.197–4.037)	4.79 (4.326–5.303)
Statistically significant differences	A6 > A12 (p < 0.01), A6 > A20 (p < 0.01), A6 > A65 (p < 0.01), A12 < A20+ (p < 0.01), A12 < A65+ (p < 0.01), A20 < A65 (p = 0.048), M < F (p < 0.01), NHW > NHB (p < 0.01), NHB < HISP (p < 0.01), NHB < OTH (p < 0.01)	A6 > A12 (p < 0.01), A6 > A20 (p < 0.01), A6 > A65 (p < 0.01), A12 < A65 (p < 0.01), A20 < A65 (p < 0.01), M < F (p < 0.01), NHW > NHB (p = 0.04), NHB < HISP (p = 0.03)
Demographic group	Creatinine corrected GM in μg/mg creatinine	Modified creatinine corrected GM in μg/mg creatinine
Urinary nitrate
Age: 6–11 years (A6)	68.039 (63.314–73.116)	89.028 (82.049–96.6)
Age: 12–19 Years (A12)	42.162 (39.563–44.932)	81.295 (76.678–86.19)
Age: 20–64 years (A20+)	48.479 (45.098–52.113)	68.696 (64.839–72.782)
Age: 65+ years (A65+)	39.44 (35.884–43.349)	46.049 (42.143–50.316)
Males (M)	44.126 (41.788–46.595)	73.911 (71.132–76.799)
Females (F)	51.442 (47.715–55.46)	62.255 (58.095–66.714)
Non-Hispanic White (NHW)	50.059 (47.084–53.222)	67.056 (62.47–71.979)
Non-Hispanic Black (NHB)	34.876 (33.115–36.729)	65.804 (63.345–68.359)
Hispanics (HISP)	45.769 (42.359–49.454)	68.158 (63.565–73.084)
Other race/ethnicities (OTH)	57.706 (52.176–63.821)	76.936 (70.328–84.165)
Statistically significant differences	A6 > A12 (p < 0.01), A6 > A20+ (p < 0.01), A6 > A65+ (p < 0.01), A12 < A20+ (p < 0.01), A20+ > A65+ (p = 0.02), M < F (p < 0.01), NHW > NHB (p < 0.01), NHW < OTH (p = 0.02), NHB < HISP (p < 0.01), NHB < OTH (p < 0.01), HISP < OTH (p < 0.01	A6 > A20+ (p < 0.01), A6 > A65+ (p < 0.01), A12 > A20+ (p < 0.01), A12 > A65+ (p = 0.04), A20+ > A65+ (p = 0.01), M < F (p < 0.01), NHW < OTH (p < 0.01), NHB < OTH (p < 0.01)
Urinary thiocyanate
Age: 6–11 years (A6)	1.277 (1.161–1.404)	1.671 (1.506–1.854)
Age: 12–19 years (A12)	0.958 (0.831–1.104)	1.847 (1.594–2.14)
Age: 20–64 years (A20+)	1.383 (1.295–1.478)	1.96 (1.847–2.08)
Age: 65+ years (A65+)	0.926 (0.81–1.058)	1.081 (0.943–1.238)
Males (M)	1.196 (1.112–1.287)	2.004 (1.851–2.17)
Females (F)	1.287 (1.171–1.413)	1.557 (1.423–1.703)
Non-Hispanic White (NHW)	1.414 (1.311–1.525)	1.894 (1.745–2.056)
Non-Hispanic Black (NHB)	1 (0.897–1.115)	1.887 (1.694–2.104)
Hispanics (HISP)	0.964 (0.822–1.13)	1.435 (1.226–1.68)
Other race/ethnicities (OTH)	0.993 (0.866–1.138)	1.324 (1.159–1.512)
Statistically significant differences	A6 > A12 (p < 0.01), A6 > A65 (p < 0.01), A12 < A20+ (p < 0.01), A20+ > A65+ (p < 0.01), NHW > NHB (p < 0.01), NHW > HISP (p < 0.01), NHW > OTH (p < 0.01)	A6 > A20+ (p < 0.01), A6 > A65+ (p < 0.01), A20+ > A65+ (p < 0.01), A20+ > A65+ (p < 0.01), M > F (p < 0.01), NHW > HISP (p < 0.01), NHW > OTH (p < 0.01), NHB > HISP (p < 0.01, NHB > OTH (p < 0.01)