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THYROID STIMULATING HORMONE (TSH-3rd Generation)

Item Value
Available Stat? No
Test code TSH3
Performed by? Chemistry
Sendout? no
Price range $$$
In House Availability Monday - Friday
Principle The Siemens Centaur assay is a two-site sandwich immunoassay using direct chemiluminometric technology.
Interpretation TSH is secreted by the anterior lobe of the pituitary gland and regulates the production of thyroid hormones by the normal thyroid gland. Under normal circumstances, the TSH levels respond to the thyroid hormone levels in the serum. Abnormal levels of thyroid hormones may result from a variety of pathologic conditions. The TSH level may aid in determining the specific cause of such conditions. High TSH values are obtained in primary hypothyroidism (thyroid gland unable to produce thyroid hormone). Low TSH values are obtained in secondary hypothyroidism (pituitary gland not secreting TSH), or hyperthyroidism.
Container type gold top gel tube
Amount to Collect 2 mL
Collection Instructions Plasma samples will not be assayed.
Sample type Blood
Normal range
Age TSH mcIU/mL
0-1 month 0.70 – 18.1
1-12 months 0.70 – 8.21
1-5 years 0.80 – 6.26
6-10 years 0.80 – 5.4
11-14 years 0.70 – 4.61
15-18 years 0.50 – 4.33
> 18 years 0.37 – 4.42




Assay is standardized against WHO 2nd IRP (80/558) Reference Material.

Recent studies suggest the upper limit of normal TSH is lower (3.0 mcIU/mL) than previously thought. We will retain our current reference range (upper limit of 4.42) but will add a statement for values between 3.0 – 4.42 mcIU/mL that reflects the newer view:

"Additional studies, including Free T4 and anti-thryoid peroxidase antibodies (AKA microsomal antibodies), may be helpful in evaluating clinical significance of a TSH value > 3.0 mcIU/mL. Pregnant patients with TSH levels > 3.0 mcIU/mL should be referred to the moderate risk obstetrics clinic."

Synonyms TSH;
Stability Serum is stable at 48 hrs at 2-8°C, 2 months at -20°C
Interferences 1. Auto- (rheumatoid factor) and heterophile antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference. Anomalous values may be observed. The most common, although not exclusive, interference seen in immunometric ("two-site," "sandwich") assays is a spuriously high value. Results inconsistent with clinical findings or previous laboratory values can be investigated by the laboratory for this phenomenon. Call the Clinical Chemistry Laboratory Medicine Resident (x65527, pager 415-443-2311).

2. A paradoxical, false low result may rarely occur when patient samples with extremely high concentrations of peptide/protein analytes (e.g. AFP, hCG, PSA, etc.) are measured by immunometric ("two-site," "sandwich") assays. For example, a true value of 3,000,000 U/L could be reported as < 5 or 21 U/L. This phenomenon is called the "high dose hook effect." Results inconsistent with clinical findings or previous laboratory values can be investigated by the laboratory for this phenomenon. Call the Clinical Chemistry Laboratory Medicine Resident (x65527, pager 415-443-2311).

3. Samples containing fluorescein can produce falsely depressed values when tested with this TSH assay. Evidence suggests that patients undergoing fluorescein dye angiography can retain small amounts of fluorescein in the body for up to 48 to 72 hours post-treatment. Samples should be re-collected and submitted post fluorescein clearance to ensure that there is no interference with TSH test results.

References 1. Bayer 111639 Rev. F, 5/2000. Siemens Medical Solutions Diagnostics, Malvern, PA.

2. Kapelari K, Kirchlechner C, Hšgler W, Schweitzer K, Virgolini I, Moncayo R. Pediatric reference intervals for thyroid hormone levels from birth to adulthood: a retrospective study. BMC Endocr Disord 8:15, 2008.
CPT coding 84443
Last Updated 4/21/2014 7:18:59 PM
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