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Thyroid Stimulating Hormone

Item Value
Test Update Information Effective 03/19/2013, the platform used for the TSH assay has changed from the Siemens DPC Immulite to the Beckman UniCel DxI 600. This assay change has little or no effect on the assay results.
Clinical Questions Does my patient have autoimmune thyroiditis?
Approval req'd? No
Available Stat? No
Test code TSH
Test group Thyroid tests
Performed by Parnassus Chemistry
In House Availability Test available 24 hours per day 7 days per week
Method Immunochemiluminescent (Beckman DxI600)
Container type Gold top or Light Green top
Amount to Collect 1.6 mL blood
Sample type Serum or heparinized plasma
Preferred volume 0.8 mL serum or heparinized plasma
Min. Volume 0.5 mL serum or heparinized plasma
Processing notes Refrigerate.
Units mIU/L
Normal range 0.45-4.12 mIU/L
Synonyms TSH; Thyrotropin
Turn around times 4 hours
Additional information The low end functional sensitivity (20% coefficient of variation cutoff) for this assay is 0.02 - 0.03 mIU/L. Reference ranges were adopted from NHANES III and verified in 170 adult blood donors negative for anti-TPO and anti-thyroglobulin antibodies (Hollowell JG et al. Serum TSH, T4, and thyroid antibodies in the United States population ,1988 to 1994: National Health and Nutrition Examination Survey , NHANES III. J Clin Endocrinol Metab 87:489–499, 2002. Garber JR et al. Clinical Practice Guidelines for Hypothyroidism in Adults: American Association of Clinical Endocrinologists and the American Thyroid Association, Thyroid 12:1200-1235, 2012).

In pregnant subjects, TSH levels decline in the first trimester and then rise after 10 -12 weeks gestation. The upper limit of normal is 2.5 mIU/L in the first trimester, 3.0 in the second trimester, and 3.5 mIU/L in the third trimester. The lower range of normal for TSH in pregnancy is 0.1 – 0.2 mIU/L lower than the normal range of non-pregnant subjects (Garber JR et al. Clinical Practice Guidelines for Hypothyroidism in Adults: American Association of Clinical Endocrinologists and the American Thyroid Association, Thyroid 12:1200-1235, 2012).

Neonatal and cord blood levels are 2-4x higher than levels at ≥ 2 weeks of age through adult life. Neonatal levels are also screened by the State program.
CPT coding 84443
Medical Necessity? Yes. Click here for more information
LOINC code 3016-3
Last Updated 2/25/2014 9:28:44 AM
Entry Number 924
Lab Procedure Link Click here for Procedure
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