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Test Code Billings Clinic: 4987 Mayo: STSH Thyroid-Stimulating Hormone-Sensitive (s-TSH), Serum

Reporting Name

TSH, Sensitive, S

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Screening for thyroid dysfunction and detecting mild (subclinical), as well as overt, primary hypo- or hyperthyroidism in ambulatory patients

 

Monitoring patients on thyroid replacement therapy

 

Confirmation of thyrotropin (TSH, formerly thyroid-stimulating hormone) suppression in thyroid cancer patients on thyroxine suppression therapy

 

Prediction of thyrotropin-releasing hormone-stimulated TSH response

Method Name

Electrochemiluminescent Immunoassay


Ordering Guidance


This is a standalone test for sensitive thyrotropin (s-TSH; formerly thyroid-stimulating hormone).

 

If a cascade approach is preferred, order THSCM / Thyroid Function Cascade, Serum, which utilizes a cascaded testing procedure to efficiently evaluate and monitor functional thyroid status. Serum s-TSH is the first-line test and when the s-TSH result is abnormal, appropriate follow-up tests will automatically be performed.



Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.6 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.


Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
  Frozen  30 days
  Ambient  7 days

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Reference Values

0-5 days: 0.7-15.2 mIU/L

6 days-2 months: 0.7-11.0 mIU/L

3-11 months: 0.7-8.4 mIU/L

1-5 years: 0.7-6.0 mIU/L

6-10 years: 0.6-4.8 mIU/L

11-19 years: 0.5-4.3 mIU/L

≥20 years: 0.3-4.2 mIU/L

 

For SI unit Reference Values, see https://www.mayocliniclabs.com/order-tests/si-unit-conversion.html

Interpretation

In primary hypothyroidism, thyrotropin (TSH, formerly thyroid-stimulating hormone) levels will be elevated. In primary hyperthyroidism, TSH levels will be low.

 

The ability to quantitate circulating levels of TSH is important in evaluating thyroid function. It is especially useful in the differential diagnosis of primary (thyroid) from secondary (pituitary) and tertiary (hypothalamus) hypothyroidism. In primary hypothyroidism, TSH levels are significantly elevated, while in secondary and tertiary hypothyroidism, TSH levels are low or normal.

 

Elevated or low TSH in the context of normal free thyroxine is often referred to as subclinical hypo- or hyperthyroidism, respectively.

 

Thyrotropin-releasing hormone (TRH) stimulation differentiates all types of hypothyroidism by observing the change in patient TSH levels in response to TRH. Typically, the TSH response to TRH stimulation is exaggerated in cases of primary hypothyroidism, absent in secondary hypothyroidism, and delayed in tertiary hypothyroidism. Most individuals with primary hyperthyroidism have TSH suppression and do not respond to TRH stimulation with an increase in TSH over their basal value.

 

Sick, hospitalized patients may have falsely low or transiently elevated TSH.

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 to 2 days

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

84443

LOINC Code Information

Test ID Test Order Name Order LOINC Value
STSH TSH, Sensitive, S 11579-0

 

Result ID Test Result Name Result LOINC Value
STSH TSH, Sensitive, S 11579-0

Testing Algorithm

See Thyroid Function Ordering Algorithm in Special Instructions.