• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Data Processing and Editing
• Laboratory Quality Assurance and Monitoring
• Analytic Notes
• Codebook
  • SEQN - Respondent sequence number
  • WTSA2YR - Two-year A subsample weights
  • LBXATG - Thyroglobulin antibodies (IU/mL)
  • LBXT3F - Triiodothyronine (T3), free (pg/mL)
  • LBXT4F - Thyroxine, free (ng/dL)
  • LBDT4FSI - Thyroxine, free (pmol/L)
  • LBXTGN - Thyroglobulin (ng/mL)
  • LBDTGNSI - Thyroglobulin (ug/L)
  • LBXTSH1 - Thyroid stimulating hormone (uIU/mL)
  • LBDTSH1S - Thyroid stimulating hormone (mIU/L)
  • LBXTPO - Thyroid perioxidase antibodies (IU/mL)
  • LBXTT3 - Triiodothyronine (T3), total (ng/dL)
  • LBDTT3SI - Triiodothyronine (T3), total (nmol/L)
  • LBXTT4 - Thyroxine, total (T4) (ug/dL)

National Health and Nutrition Examination Survey

2009-2010 Data Documentation, Codebook, and Frequencies

Thyroid Profile (THYROD_F)

Data File: THYROD_F.xpt

First Published: September 2011

Last Revised: October 2015

Component Description

The Thyroid Profile consists of a battery of several tests for the measurement of thyroid function, including Total and Free Thyroxine, Total and Free Triiodothyronine, Thyroglobulin, Thyroglobulin Antibodies, Thyroid Peroxidase Antibodies, and Thyroid Stimulating Hormone. Thyroid function is crucial for maintaining normal metabolic function in adults and for proper neurological development of the fetus. Serum levels will be used to assess thyroid function and will provide population-based reference information on these hormone levels.

Eligible Sample

A one-third sample of participants aged 12 years and older, who do not meet any of the exclusion criteria, are eligible.

Description of Laboratory Methodology

Thyroid blood specimens were processed, stored and shipped to University of Washington, Seattle, WA. Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM).

Thyroid-stimulating hormone

The Access HYPERsensitive human thyroid-stimulating hormone (hTSH) assay is a 3^rd generation, two-site immunoenzymatic (“sandwich”) assay. A sample is added to a reaction vessel with goat anti-hTSH-alkaline phosphatase conjugate, buffered protein solution, and paramagnetic particles coated with immobilized mouse monoclonal anti-hTSH antibody. (Goat anti-mouse antibody is used to immobilize the mouse anti-hTSH antibody.) The hTSH binds to the immobilized monoclonal anti-hTSH on the solid phase while the goat anti-hTSH-alkaline phosphatase conjugate reacts with a different antigenic site on the hTSH. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate Lumi-Phos™ 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of human thyroid-stimulating hormone in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Human TSH is one of several glycoprotein hormones consisting of two non-covalently bound peptide chains: an a-chain, which is nearly identical in all, and a ß-chain, which is responsible for immunological and biological specificity. These similarities result in varying degrees of cross-reactivity of different antisera. The Access HYPERsensitive hTSH assay has virtually no cross-reactivity with other peptide hormones. The sensitivity and specificity of this test enable better discrimination between hyperthyroid and euthyroid patients.

Total T3 assay

The Access Total T3 assay is a competitive binding immunoenzymatic assay. Sample is added to a reaction vessel with a stripping agent to dissociate T3 from the binding proteins. T3 in the sample competes with the T3 analogue coupled to biotin for anti-T3 alkaline phosphatase conjugate. Of the resulting antigen/antibody complexes, the T3 analogue/antibody complexes are bound to the streptavidin coated solid phase. Separation in a magnetic field and washing removes the sample T3/antibody complexes and other materials not bound to the solid phase. Then, the chemiluminescent substrate Lumi-Phos™ 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of total T3 in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Free T3 assay

Access Free T3 assay is a competitive binding immunoenzymatic assay. A sample is added to a reaction vessel with an anti-T3 monoclonal antibody conjugated to alkaline phosphatase. During the incubation, free T3 in the sample reacts with the anti-T3 antibody. Particles coated with streptavidin and biotinylated T3 analog are then added to the mixture. Unoccupied binding sites on the anti-T3 antibody are bridged to the particle through the T3 analog. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate Lumi-Phos™ 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of free T3 in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Total T4 assay

The Access Total T4 assay is a competitive binding immunoenzymatic assay. A sample is added to a reaction vessel with anti-thyroxine antibody, thyroxine-alkaline phosphatase conjugate, and paramagnetic particles coated with goat anti-mouse capture antibody and a stripping agent to dissociate all T4 from binding proteins. Thyroxine in the sample competes with the thyroxine-alkaline phosphatase conjugate for binding sites on a limited amount of specific anti-thyroxine antibody. Resulting antigen: antibody complexes bind to the capture antibody on the solid phase. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate Lumi-Phos™ 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of thyroxine in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Free T4 assay

The Access Free T4 (FRT4) assay is a two-step enzyme immunoassay. Monoclonal anti-Thyroxine (T4) antibody coupled to biotin, sample, buffered protein solution, and streptavidin-coated solid phase are added to the reaction vessel. During this first incubation, the anti-T4 antibody coupled to biotin binds to the solid phase and the free T4 in the sample. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Next, buffered protein solution and triiodothyronine (T3)-alkaline phosphatase conjugate are added to the reaction vessel. The T3-alkaline phosphatase conjugate binds to the vacant anti-T4 antibody binding sites. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate Lumi-Phos™ 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of free T4 in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Thyroglobulin (Tg) assay

The Access thyroglobulin (Tg) assay is a simultaneous one-step "sandwich" assay. A sample is added to a reaction vessel, along with biotinylated mixture of four monoclonal anti-Tg antibodies, streptavidin coated paramagnetic particles, and monoclonal anti-Tg antibody alkaline phosphatase conjugate. The biotinylated antibodies and the serum or plasma thyroglobulin bind to the solid phase, while the conjugate antibody reacts with a different antigenic site on the thyroglobulin molecule. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. A chemiluminescent substrate, Lumi-Phos** 530 is added to the reaction vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of thyroglobulin in the sample. The amount of Thyroglobulin in the sample is determined by means of a stored, multi-point calibration curve.

Thyroglobulin antibody assay (TgAb)

The Access thyroglobulin antibody assay is a sequential two-step immunoenzymatic "sandwich" assay. A sample is added to a reaction vessel with paramagnetic particles coated with the thyroglobulin protein. After incubation, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. The thyroglobulin-alkaline phosphatase conjugate is added and binds to the TgAb. After a second incubation, the reaction vessel is washed to remove unbound materials. A chemiluminescent substrate, Lumi-Phos™ 530 is added to the reaction vessel and light generated by the reaction is measured with a luminometer. The light production is proportional to the concentration of Thyroglobulin antibody in the sample. The amount of Thyroglobulin antibody in the sample is determined by means of a stored, multi-point calibration curve.

Thyroid peroxidase antibody

The Access TPO antibody (TPOAb) assay is a sequential two-step immunoenzymatic "sandwich" assay. A sample is added to a reaction vessel with paramagnetic particles coated with the thyroid peroxidase protein. After an incubation, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. The protein A-alkaline phosphatase conjugate is added and binds to the TPOAb. After a second incubation, the reaction vessel is washed to remove unbound materials. A chemiluminescent substrate, Lumi-Phos™ 530 is added to the reaction vessel and light generated by the reaction is measured with a luminometer. The light production is proportional to the concentration of TPO antibody in the sample. The amount of TPOAb in the sample is determined by means of a stored, multi-point calibration curve.

Data Processing and Editing

Read the General Documentation on Laboratory Data file for detailed data processing and editing protocols. The analytical methods are described in the Description of the Laboratory Methodology section.

Five variables in this data file were created. The formula for their creation is as follows:

Free thyroxine results (LBXT4F) in ng/dL were multiplied by 12.9 into pmol/L (LBDT4FSI).

Thyroglobin results LBXTGN) in ng/mL were multiplied by 1.0 into µg/L (LBDTGNSI).

Thyroid stimulating hormone results (LBXTSH1) in µIU/mL were multiplied by 1.0 into mIU/L (LBDTSH1S).

Total triiodothyronine results (LBXTT3) in ng/dL were multiplied by .0154 into nmol/L (LBDTT3SI).

Total triiodothyronine results (LBXTT3) in ng/dL were multiplied by .0154 into nmol/L (LBDTT3SI).

The variable named LBD___LC indicates whether the result was below the limit of detection. There are two values: “0” and “1””. “0” means that the result was at or above the limit of detection. “1” indicates that the result was below the limit of detection

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 LPM. Read the General Documentation on Laboratory Data file for detailed QA/QC protocols.

A detailed description of the quality assurance and quality control procedures can be found on the NHANES website.

Analytic Notes

Analytic Note for 2009-2010 Total Thyroxine:

In 2009-2010, there was a change in laboratories performing the total thyroxine (TT4). The TT4 was performed at the University of Washington Medical Center, Department of Laboratory Medicine in 2009 and the TT4 was performed at the Collaborative Laboratory Services (CLS) in 2010. Both laboratories used a competitive binding immunoenzymatic assay on the Beckman Coulter Access 2 analyzer. A crossover study of 113 specimens was performed between the two laboratories and the CLS laboratory values had a higher mean and median compared to the University of Washington by approximately 5%. This was also seen in the sample participants when comparing 2009 and 2010 TT4 distributions. The difference in TT4 results may have been due to different lots of calibrators and reagents. Using a fractional polynomial regression, the 2010 TT4 participant results were lowered to compare to the 2009 TT4 results.

NHANES survey analysis:

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The Demographic file contains: Status Variables providing core information on the survey participant including examination status, Recoded Demographic Variables including age, gender, race etc., and Interview and Examination Sample Weight Variables and Survey Design Variables. The Questionnaire Data Files contain socio-economic data, health indicators, and other related information collected during household interviews. The Phlebotomy Examination file includes auxiliary information on duration of fasting, the time of day of the venipuncture, and the conditions precluding venipuncture. The Demographic, Questionnaire and Phlebotomy Examination files may be linked to the laboratory data file using the unique survey participant identifier SEQN.

Exam sample weights should be used for analyses. 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.

Codebook and Frequencies