Test Catalog

Test Id : THSCM

Thyroid Function Cascade, Serum

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for a diagnosis of thyroid disease

Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.

Test Id Reporting Name Available Separately Always Performed
STSHC TSH, Sensitive, S Yes, Bill Only Yes

Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.

Test Id Reporting Name Available Separately Always Performed
FRT4C T4 (Thyroxine), Free, S Yes, Bill Only No
TPOC Thyroperoxidase Ab, S Yes, Bill Only No
T3C T3 (Triiodothyronine), Total, S Yes, Bill Only No

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If thyrotropin (TSH, formerly thyroid-stimulating hormone) is <0.3 mIU/L, then free T4 (FT4) is performed at an additional charge.

 

If FT4 is normal and the TSH is <0.1 mIU/L, then triiodothyronine (T3) is performed at an additional charge.

 

If TSH is >4.2 mIU/L, then FT4 and thyroperoxidase antibodies are performed at an additional charge.

 

See Thyroid Function Ordering Algorithm in Special Instructions.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Electrochemiluminescent Immunoassay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Thyroid Function Cascade, S

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If thyrotropin (TSH, formerly thyroid-stimulating hormone) is <0.3 mIU/L, then free T4 (FT4) is performed at an additional charge.

 

If FT4 is normal and the TSH is <0.1 mIU/L, then triiodothyronine (T3) is performed at an additional charge.

 

If TSH is >4.2 mIU/L, then FT4 and thyroperoxidase antibodies are performed at an additional charge.

 

See Thyroid Function Ordering Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

Serum

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1.5 mL

Collection Instructions:

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

2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

1 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 7 days
Frozen 30 days
Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Screening for a diagnosis of thyroid disease

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If thyrotropin (TSH, formerly thyroid-stimulating hormone) is <0.3 mIU/L, then free T4 (FT4) is performed at an additional charge.

 

If FT4 is normal and the TSH is <0.1 mIU/L, then triiodothyronine (T3) is performed at an additional charge.

 

If TSH is >4.2 mIU/L, then FT4 and thyroperoxidase antibodies are performed at an additional charge.

 

See Thyroid Function Ordering Algorithm in Special Instructions.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

This test utilizes a cascaded testing procedure to efficiently evaluate and monitor functional thyroid status. 

 

The cascade begins with thyrotropin (TSH, formerly thyroid-stimulating hormone) as a screening assay. In patients with an intact pituitary-thyroid axis, TSH provides a physiologic indicator of the functional level of thyroid hormone activity. Increased TSH indicates inadequate thyroid hormone, and suppressed TSH indicates excess thyroid hormone.

 

Transient TSH abnormalities may be found in seriously ill, hospitalized patients, so this is not the ideal setting to assess thyroid function. However, even in these patients, TSH works better than total thyroxine (an alternative screening test).

 

When TSH is normal, no additional testing will be necessary. However, when the TSH result is abnormal, appropriate follow-up tests will automatically be performed.

 

If TSH is below 0.3 mIU/L or above 4.2 mIU/L, free thyroxine (FT4) is performed. The supplemental measurement of FT4 in patients with abnormal TSH measurements allows one to better assess the severity of the changes.

 

Serum triiodothyronine (T3) levels often are depressed in sick and hospitalized patients, caused in part by the biochemical shift to the production of reverse T3. Therefore, T3 generally is not a reliable predictor of hypothyroidism. However, in a small subset of hyperthyroid patients, hyperthyroidism may be caused by overproduction of T3 (T3 toxicosis). To help diagnose and monitor this subgroup, T3 is measured on all specimens with suppressed TSH and normal FT4 concentrations.

 

Detectable concentrations of antithyroperoxidase (anti-TPO) antibodies are observed in patients with autoimmune thyroiditis and may cause the destruction of thyroid tissue, eventually resulting in hypothyroidism. Anti-TPO antibodies are measured in all specimens with elevated TSH concentrations.

 

See Thyroid Function Ordering Algorithm in Special Instructions.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

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

> or =20 years: 0.3-4.2 mIU/L

Interpretation
Provides information to assist in interpretation of the test results

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 test with an increase in TSH over their basal value.

 

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

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Serum biotin concentrations up to 1200 ng/mL do not interfere with this assay. Concentrations up to 1200 ng/mL may be present in specimens collected from patients taking extremely high doses of biotin up to 300 mg per day.(1)  In a study among 54 healthy volunteers, supplementation with 20 mg/day biotin resulted in a maximum serum biotin concentration of 355 ng/mL 1 hour post-dose.(2)

 

For assays employing antibodies, the possibility exists for interference by human anti-animal antibodies (ie, heterophile antibodies) in the patient specimen. Patients who have been regularly exposed to animals or have received immunotherapy or diagnostic procedures utilizing immunoglobulins or immunoglobulin fragments may produce antibodies (eg, human antimouse antibodies) that interfere with immunoassays. This may falsely elevate or falsely decrease the results. Interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.

 

For diagnostic purposes, the results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.(3)

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Saint Paul LP, Debruyne D, Bernard D, Mock DM, Defer GL: Pharmacokinetics and pharmacodynamics of MD1003 (high-dose biotin) in the treatment of progressive multiple sclerosis. Expert Opin Drug Metab Toxicol. 2016;12(3):327-344. doi: 10.1517/17425255.2016.1136288.

2. Grimsey P, Frey N, Bendig G, et al: Population pharmacokinetics of exogenous biotin and the relationship between biotin serum levels and in vitro immunoassay interference. J Pharmacokinet Pharmacodyn. 2017;2(4),247-256

3. Package insert: TSH Reagent. Roche Diagnostics; V2, 03/2020

4. Fatourechi V, Lankarani M, Schryver P, Vanness DJ, Long KH, Klee GG: Factors influencing clinical decisions to initiate thyroxine therapy for patients with mildly increased serum thyrotropin (5.1-10.0 mIU/L). Mayo Clin Proc. 2003 May;78(5):554-560. doi: 10.4065/78.5.554

5. Wilson JD, Foster D, Kronenburg HM, et al: Williams Textbook of Endocrinology. 9th ed. WB Saunders Company; 1998

6. Melmed S, Polonsky KS, Larsen PR, et al: Williams Textbook of Endocrinology. 12th ed. Elsevier Saunders Company; 2011:348-414

7. Heil W, Ehrhardt V: Reference Intervals for Adults and Children 2008. 9th ed. Roche Diagnostics; 09/2009

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

The cobas e immunoassay thyroid-stimulating hormone (TSH) method employs monoclonal antibodies specifically directed against human TSH. A biotinylated monoclonal TSH-specific antibody and a monoclonal TSH-specific antibody labeled with a ruthenium complex react to form a sandwich complex. After the addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Application of a voltage to the electrode then induces chemiluminescent emission, which is measured by a photomultiplier.(Package insert: Thyrotropin TSH, Roche Diagnostics Corporation, Indianapolis IN)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 2 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

84443-Thyroid-stimulating hormone-sensitive (s-TSH)

84439-T4 (thyroxine), free (if appropriate)

84480-T3 (triiodothyronine), total (if appropriate)

86376-Thyroperoxidase (TPO) antibodies (if appropriate)

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports