Table of Contents

Locator Record

Title: Serum transferrin receptor and serum ferritin (Surplus Sera) (SSTFR_B )
Contact Number: 1-866-441-NCHS
Years of Content: 2001 - 2002
First Published: July, 2008
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Transferrin receptor and serum ferritin
Record Source: NHANES 2001 - 2002
Survey Methodology: NHANES 2001 - 2002 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

Serum transferrin receptor and ferritin were measured in pregnant women from NHANES 2001-2002 to provide estimates of iron deficiency based on body iron levels observed in these women. Body iron estimates can be predicted using an equation that includes measured serum transferrin receptor and serum ferritin levels. Serum transferrin receptor was not added to NHANES until 2003. Serum ferritin was measured in NHANES 2001-2002 with a method that has now been shown to differ from the method needed to provide the appropriate ferritin values for use in the body iron model equation. Thus, serum ferritin was re-measured using the appropriate method for body iron calculations.

Eligible Sample

Pregnant women aged 13 to 56 years from NHANES 2001-2002 with stored sera (N = 625). The pregnant women for this sample were identified using either one of the two available summary pregnancy variables (RIDEXPRG or RIDPREG) or in the case of 20 women < 18 years of age from NHANES 1999-2000, with the self-reported pregnancy item RHQ140. This item was used for these 20 women because RIDEXPRG and RIDPREG were not provided for women < 18 years of age in NHANES 1999-2000.

Description of Laboratory Methodology

The method for measurement of soluble transferrin receptor (sTfR) is immuno-turbidimetry using Roche kits on the Hitachi 912 clinical analyzer. Latex bound anti-sTfR antibodies react with the antigen in the sample to form an antigen/antibody complex. Following agglutination, this is measured turbidimetrically. This is the same method used to measures sTfR starting in NHANES 2003+.

The method principle for measurement of Ferritin is immuno-turbidimetry using the Roche/Hitachi 912 clinical analyzer. Latex bound Ferritin antibodies react with the antigen in the sample to form an antigen/antibody complex. Following agglutination, this is measured turbidimetrically. Complexes formed are proportional to the Ferritin concentration, and were measured at 700nm (primary wavelength). This is the same method used to measure serum ferritin starting in NHANES 2004. These ferritin data do not need to be adjusted to be compared with NHANES 2003-2004 ferritin data.

Data Processing and Editing

Data was received after the sTfR and ferritin assays were complete. The data were not edited.

Data Access: All data are publicly available.

Laboratory Quality Assurance and Monitoring

The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed quality control and quality assurance instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). A detailed description of the quality assurance and quality control procedures can be found at NHANES web site.

Analytic Notes

There are two variables:

LBXTFR: serum transferrin receptor (mg/L)
LBXFER: Serum ferritin (ng/mL)

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Females only 13 YEARS - 56 YEARS

SSTFR - Serum transferrin receptor (mg/l)

Variable Name:
SSTFR
SAS Label:
Serum transferrin receptor (mg/l)
English Text:
Serum transferrin receptor (mg/l)
Target:
Females only 13 YEARS - 56 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.5 to 18 Range of Values 343 343
. Missing 0 343

SSFER - Serum ferritin (ng/ml)

Variable Name:
SSFER
SAS Label:
Serum ferritin (ng/ml)
English Text:
Serum ferritin (ng/ml)
Target:
Females only 13 YEARS - 56 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3 to 394 Range of Values 343 343
. Missing 0 343