Table of Contents

Locator Record

Title: Sodium, potassium, and chloride in casual urine (SSUE10_R )
Contact Number: 1-866-441-NCHS
Years of Content: 2010 - 2010
First Published: September, 2012
Revised: NA
Access Constraints: RDC Only
Use Constraints: RDC Only
Geographic Coverage: National
Subject:Sodium, potassium, and chloride in casual urine
Record Source: NHANES 2010 - 2010
Survey Methodology: NHANES 2010 - 2010 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

Measurement of sodium, potassium, and chloride in a subset of stored casual urine samples from NHANES 2010.

Eligible Sample

1,275 participants aged 6 years and above from a one-third subsample of NHANES 2010 (for which urine iodine values are available) who provided a casual urine sample at the Mobile Examination Center and 1,345 participants aged 6 years and above from the same one-third subsample of NHANES 2010 who provided a first-morning void urine sample for a total of 2,620 samples; most participants provided both types of samples

Description of Laboratory Methodology

Measurement of Urine Sodium, Potassium, and Chloride

All assays were conducted using the Cobas ISE/Na+, K+, Cl- assay performed on the Roche Modular P instrument. The measurement of electrolytes in urine via ion-selective electrode (ISE) is an established and widely used procedure in routine clinical laboratories. The ISE makes use of the unique properties of certain membrane materials to develop an electrical potential for the measurement of ions in solution. The method quantitatively determines sodium, potassium and chloride in urine. The manufacturer has standardized this method against primary calibrators prepared gravimetrically from purified salts. Two levels of standard are provided by the manufacturer for daily calibration. The volume of urine needed per test is 150 µL (combined measurement of sodium, potassium, and chloride). 

Analyte codes and limits of detection (LOD):
Analyte name Analyte code LOD (mmol/L)
Urine sodium (Na+) UNA 10
Urine potassium (K+) UK 1.5
Urine chloride (Cl-) UCL 10

Data Processing and Editing

Data were received after all the laboratory testing was complete. The data were not edited for extreme values.

Data will only be available through the Research Data Center.

Laboratory Quality Assurance and Monitoring

The laboratory and method were certified according to the Clinical Laboratory Improvement Amendment (1988) guidelines.

For urine Na+, K+ and Cl- , commercially prepared quality control material was purchased from CLINIQA in two levels (LIQUID QCTM 1 and LIQUID QCTM 2). The controls are liquid and ready for use. Stability of the constituents at 2-8°C is 36 months or until the expiration date, whichever comes first. Bench QC pools were characterized to determine the mean and control limits by analyzing duplicate samples in at least 20 runs. After establishment of the control limits of the pools, QC samples contained within each analytical run were evaluated for validity by use of a multi-rule quality control program.

Performance of QC pools during the study period (Aug – Oct 2011):
QC Pool Analyte N Mean (mmol/L) SD (mmol/L) CV (%)
LIQUID QCTM 1 UNA 64 67.7 1.23 1.8%
LIQUID QCTM 2 UNA 64 158 0.92 0.6%
LIQUID QCTM 1 UK 64 29.5 0.55 1.9%
LIQUID QCTM 2 UK 64 80.6 2.34 2.9%
LIQUID QCTM 1 UCL 64 84.1 1.13 1.3%
LIQUID QCTM 2 UCL 64 190 1.56 0.8%

The laboratory achieved satisfactory participation in the CAP proficiency testing surveys during 2011 for the urine chemistry surveys for sodium, potassium, and chloride and for the linearity and calibration verification surveys for sodium.

The laboratory also included blind QC samples (high or low pool) in each run at a rate of 1 blind QC in every 20 samples. These samples were labeled the same as unknown participant samples and therefore remained unrecognized by the analyst.

Performance of blind QC pools during the study period:
Blind QC Pool Analyte N Mean (mmol/L) SD (mmol/L) CV
Low UNA 61 165 0.94 0.6%
High UNA 64 56.6 1.04 1.8%
Low UK 61 79.8 2.42 3.0%
High UK 64 38.6 0.74 1.9%
Low UCL 61 182 2.12 1.2%
High UCL 64 57.4 0.84 1.5%

Analytic Notes

Samples were selected from the 1/3 urinary iodine subsample for sample participants aged 6 and over that provided informed consent for further testing of stored specimen and had a non-missing urinary creatinine measure. In addition, 55 sample participants with untreated hypertension from the full examination sample (not already included in the1/3 urinary iodine subsample) that provided informed consent for further testing of stored specimen and had a non-missing urinary creatinine measure were selected.

Weights were created to account for non-response and to sum to the examination weights for 2010. The adjustment factors were based on age categories, race and Hispanic origin, and gender. The data were collected only for a single year (2010) rather than a typical NHANES 2-year data collection period, therefore, the single year urine sodium weight, WTFIN, should be used in estimating the prevalence and in testing statistical hypotheses using these data. The delete 1 Jackknife method rather than Taylor Series Linearization is recommended for variance estimation (Wolters, 2007). The delete 1 Jackknife method is a replication method, using a design based method for variance estimation. Fifteen delete 1 jackknife replicate weights, WTFIN01-WTFIN15, are provided for variance estimation using the delete 1 Jackknife method. To calculate the nominal degrees of freedom of the estimated variance, unmasked variance units (which differ from the Masked Variance Unit codes provided for the two year public-use files) are provided. These unmasked variance units are needed to determine the critical value for the Student’s t statistic used to construct confidence intervals.

All statistical analyses using these data should assess the relative standard error of the estimates, the degrees of freedom and the design effect. The three diagnostics listed above are important to assess the reliability of the estimates. Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues. Both of these are available on the NHANES website.

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 6 YEARS - 150 YEARS

SSUNAMP - Urine Sodium (mmol/L) MEC spot urine

Variable Name:
SSUNAMP
SAS Label:
Urine Sodium (mmol/L) MEC spot urine
English Text:
Urine Sodium (mmol/L) MEC spot urine
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 324 Range of Values 1275 1275
. Missing 211 1486

SSUNAHP - Na (mmol/L) Urine first morning void

Variable Name:
SSUNAHP
SAS Label:
Na (mmol/L) Urine first morning void
English Text:
Urine Sodium (mmol/L) First morning void
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 359 Range of Values 1345 1345
. Missing 141 1486

SSUKMP - Urine Potassium (mmol/L) MEC spot urine

Variable Name:
SSUKMP
SAS Label:
Urine Potassium (mmol/L) MEC spot urine
English Text:
Urine Potassium (mmol/L)
English Instructions:
Urine Potassium (mmol/L) MEC spot urine
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2.3 to 212 Range of Values 1275 1275
. Missing 211 1486

SSUKHP - K (mmol/L) Urine first morning void

Variable Name:
SSUKHP
SAS Label:
K (mmol/L) Urine first morning void
English Text:
Urine Potassium (mmol/L) First morning void
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2.3 to 207 Range of Values 1345 1345
. Missing 141 1486

SSUCLMP - Urine Chloride (mmol/L) MEC spot urine

Variable Name:
SSUCLMP
SAS Label:
Urine Chloride (mmol/L) MEC spot urine
English Text:
Urine Chloride (mmol/L)
English Instructions:
Urine Chloride (mmol/L) MEC spot urine
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 369 Range of Values 1275 1275
. Missing 211 1486

SSUCLHP - Cl (mmol/L) Urine first morning void

Variable Name:
SSUCLHP
SAS Label:
Cl (mmol/L) Urine first morning void
English Text:
Urine Chloride (mmol/L) First morning void
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 330 Range of Values 1345 1345
. Missing 141 1486

T_VPSU - Taylor Series-Variance PSU Identifier

Variable Name:
T_VPSU
SAS Label:
Taylor Series-Variance PSU Identifier
English Text:
Taylor Series-Variance PSU Identifier
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 2 Range of Values 1486 1486
. Missing 0 1486

T_VSTRAT - Taylor Series-Variance Strata Identifier

Variable Name:
T_VSTRAT
SAS Label:
Taylor Series-Variance Strata Identifier
English Text:
Taylor Series-Variance Strata Identifier
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 to 15 Range of Values 1486 1486
. Missing 0 1486

WTNA - Subsample weight

Variable Name:
WTNA
SAS Label:
Subsample weight
English Text:
Subsample weight
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
25621.367314 to 959210.92414 Range of Values 1486 1486
. Missing 0 1486

WTNA01 - Subsample weight 01

Variable Name:
WTNA01
SAS Label:
Subsample weight 01
English Text:
Subsample weight 01
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26387.255629 to 961704.40922 Range of Values 1395 1395
. Missing 91 1486

WTNA02 - Subsample weight 02

Variable Name:
WTNA02
SAS Label:
Subsample weight 02
English Text:
Subsample weight 02
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26458.05939 to 991268.17114 Range of Values 1390 1390
. Missing 96 1486

WTNA03 - Subsample weight 03

Variable Name:
WTNA03
SAS Label:
Subsample weight 03
English Text:
Subsample weight 03
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
27403.664273 to 957744.49679 Range of Values 1401 1401
. Missing 85 1486

WTNA04 - Subsample weight 04

Variable Name:
WTNA04
SAS Label:
Subsample weight 04
English Text:
Subsample weight 04
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
25612.525655 to 975509.65316 Range of Values 1391 1391
. Missing 95 1486

WTNA05 - Subsample weight 05

Variable Name:
WTNA05
SAS Label:
Subsample weight 05
English Text:
Subsample weight 05
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26378.005169 to 905227.92819 Range of Values 1398 1398
. Missing 88 1486

WTNA06 - Subsample weight 06

Variable Name:
WTNA06
SAS Label:
Subsample weight 06
English Text:
Subsample weight 06
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26414.359601 to 910820.63591 Range of Values 1398 1398
. Missing 88 1486

WTNA07 - Subsample weight 07

Variable Name:
WTNA07
SAS Label:
Subsample weight 07
English Text:
Subsample weight 07
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
31842.039423 to 951626.02853 Range of Values 1404 1404
. Missing 82 1486

WTNA08 - Subsample weight 08

Variable Name:
WTNA08
SAS Label:
Subsample weight 08
English Text:
Subsample weight 08
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
25444.144595 to 955590.49049 Range of Values 1367 1367
. Missing 119 1486

WTNA09 - Subsample weight 09

Variable Name:
WTNA09
SAS Label:
Subsample weight 09
English Text:
Subsample weight 09
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26203.411756 to 902748.59802 Range of Values 1386 1386
. Missing 100 1486

WTNA10 - Subsample weight 10

Variable Name:
WTNA10
SAS Label:
Subsample weight 10
English Text:
Subsample weight 10
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
30622.984361 to 932016.7525 Range of Values 1350 1350
. Missing 136 1486

WTNA11 - Subsample weight 11

Variable Name:
WTNA11
SAS Label:
Subsample weight 11
English Text:
Subsample weight 11
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
28149.487794 to 956529.7517 Range of Values 1400 1400
. Missing 86 1486

WTNA12 - Subsample weight 12

Variable Name:
WTNA12
SAS Label:
Subsample weight 12
English Text:
Subsample weight 12
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
26893.934761 to 987792.43183 Range of Values 1380 1380
. Missing 106 1486

WTNA13 - Subsample weight 13

Variable Name:
WTNA13
SAS Label:
Subsample weight 13
English Text:
Subsample weight 13
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
28597.978993 to 989931.12685 Range of Values 1369 1369
. Missing 117 1486

WTNA14 - Subsample weight 14

Variable Name:
WTNA14
SAS Label:
Subsample weight 14
English Text:
Subsample weight 14
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
28808.888027 to 973951.60129 Range of Values 1392 1392
. Missing 94 1486

WTNA15 - Subsample weight 15

Variable Name:
WTNA15
SAS Label:
Subsample weight 15
English Text:
Subsample weight 15
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
29591.425207 to 979726.33704 Range of Values 1383 1383
. Missing 103 1486