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Second-trimester reference intervals for thyroid tests: the role of ethnicity.

Abstract

BACKGROUND

Thyroid function changes during pregnancy, complicating the diagnosis of thyroid disorders. Maternal thyroid dysfunction has been associated with a variety of adverse outcomes. We evaluated thyroid function test results by ethnicity and week of gestation during the 2nd trimester of pregnancy.

METHODS

We collected 3064 blood specimens in serum tubes from Asians (13%), blacks (22%), Hispanics (23%), and whites (42%). We measured thyroid-stimulating hormone (TSH), total and free thyroxine (TT4 and FT4), total and free triiodothyronine (TT3 and FT3), thyroglobulin autoantibodies (TgAb), and thyroid peroxidase autoantibodies (TPOAb) by use of an ARCHITECT i2000(SR) (Abbott Diagnostics). The TSH reference interval was calculated for samples negative for both TgAb and TPOAb and reference intervals for TT4, FT4, TT3, and FT3 in antibody-negative samples with normal TSH.

RESULTS

Serum samples were positive for TgAb in 10.6%, 1.8%, 6.2%, 6.5%, and 5.9% of Asian, black, Hispanic, white, and combined groups, respectively. Samples were positive for TPOAb in 12.4%, 4.1%, 11.8%, 12.3%, and 10.4% of the same groups, respectively. The nonparametric reference intervals for all participants were 0.15-3.11 mIU/L (TSH), 9.3-15.2 pmol/L (0.72-1.18 ng/dL; FT4), 89.0-176.3 nmol/L (6.90-13.67 mug/dL; TT4), 3.82-5.96 pmol/L (2.48-3.87 pg/mL; FT3), and 1.82-3.68 nmol/L (118-239 ng/dL; TT3).

CONCLUSIONS

Blacks had lower prevalences of TgAb and TPOAb positivity and of increased serum TSH. The prevalence of TgAb and TPOAb positivity was highest in Asians. Whites had the highest prevalence of increased TSH. The lower and upper reference limits of TT3 were significantly lower for Asians. Reference intervals for women in the 2nd trimester were different from those of nonpregnant individuals.

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  • Authors+Show Affiliations

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    ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT, USA.

    Source

    Clinical chemistry 53:9 2007 Sep pg 1658-64

    MeSH

    Adolescent
    Adult
    African Continental Ancestry Group
    Asian Americans
    Autoantibodies
    Autoantigens
    Chorionic Gonadotropin
    Continental Population Groups
    European Continental Ancestry Group
    Female
    Hispanic Americans
    Humans
    Iodide Peroxidase
    Iron-Binding Proteins
    Middle Aged
    Pregnancy
    Pregnancy Trimester, Second
    Reference Values
    Thyroglobulin
    Thyroid Function Tests
    Thyroid Gland
    Thyrotropin
    Thyroxine
    Triiodothyronine

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    17712003

    Citation

    La'ulu, Sonia L., and William L. Roberts. "Second-trimester Reference Intervals for Thyroid Tests: the Role of Ethnicity." Clinical Chemistry, vol. 53, no. 9, 2007, pp. 1658-64.
    La'ulu SL, Roberts WL. Second-trimester reference intervals for thyroid tests: the role of ethnicity. Clin Chem. 2007;53(9):1658-64.
    La'ulu, S. L., & Roberts, W. L. (2007). Second-trimester reference intervals for thyroid tests: the role of ethnicity. Clinical Chemistry, 53(9), pp. 1658-64.
    La'ulu SL, Roberts WL. Second-trimester Reference Intervals for Thyroid Tests: the Role of Ethnicity. Clin Chem. 2007;53(9):1658-64. PubMed PMID: 17712003.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Second-trimester reference intervals for thyroid tests: the role of ethnicity. AU - La'ulu,Sonia L, AU - Roberts,William L, PY - 2007/8/23/pubmed PY - 2007/9/29/medline PY - 2007/8/23/entrez SP - 1658 EP - 64 JF - Clinical chemistry JO - Clin. Chem. VL - 53 IS - 9 N2 - BACKGROUND: Thyroid function changes during pregnancy, complicating the diagnosis of thyroid disorders. Maternal thyroid dysfunction has been associated with a variety of adverse outcomes. We evaluated thyroid function test results by ethnicity and week of gestation during the 2nd trimester of pregnancy. METHODS: We collected 3064 blood specimens in serum tubes from Asians (13%), blacks (22%), Hispanics (23%), and whites (42%). We measured thyroid-stimulating hormone (TSH), total and free thyroxine (TT4 and FT4), total and free triiodothyronine (TT3 and FT3), thyroglobulin autoantibodies (TgAb), and thyroid peroxidase autoantibodies (TPOAb) by use of an ARCHITECT i2000(SR) (Abbott Diagnostics). The TSH reference interval was calculated for samples negative for both TgAb and TPOAb and reference intervals for TT4, FT4, TT3, and FT3 in antibody-negative samples with normal TSH. RESULTS: Serum samples were positive for TgAb in 10.6%, 1.8%, 6.2%, 6.5%, and 5.9% of Asian, black, Hispanic, white, and combined groups, respectively. Samples were positive for TPOAb in 12.4%, 4.1%, 11.8%, 12.3%, and 10.4% of the same groups, respectively. The nonparametric reference intervals for all participants were 0.15-3.11 mIU/L (TSH), 9.3-15.2 pmol/L (0.72-1.18 ng/dL; FT4), 89.0-176.3 nmol/L (6.90-13.67 mug/dL; TT4), 3.82-5.96 pmol/L (2.48-3.87 pg/mL; FT3), and 1.82-3.68 nmol/L (118-239 ng/dL; TT3). CONCLUSIONS: Blacks had lower prevalences of TgAb and TPOAb positivity and of increased serum TSH. The prevalence of TgAb and TPOAb positivity was highest in Asians. Whites had the highest prevalence of increased TSH. The lower and upper reference limits of TT3 were significantly lower for Asians. Reference intervals for women in the 2nd trimester were different from those of nonpregnant individuals. SN - 0009-9147 UR - https://www.unboundmedicine.com/medline/citation/17712003/Second_trimester_reference_intervals_for_thyroid_tests:_the_role_of_ethnicity_ L2 - http://www.clinchem.org/cgi/pmidlookup?view=long&pmid=17712003 DB - PRIME DP - Unbound Medicine ER -