Test Id : THCSM
Thyroid Function Cascade, Monitor (without Thyroid Peroxidase Antibody), Serum
Useful For
Suggests clinical disorders or settings where the test may be helpful
Monitoring patients diagnosed with thyroid disease
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 | No |
| T3C | T3 (Triiodothyronine), Total, S | Yes | No |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If thyrotropin (TSH) is less than 0.3 mIU/L, then free T4 (FT4, thyroxine) will be performed at an additional charge.
If free T4 is normal and the TSH is less than 0.1 mIU/L, then T3 (triiodothyronine) will be performed at an additional charge.
If TSH is greater than 4.2 mIU/L, then free T4 will be performed at an additional charge.
Method Name
A short description of the method used to perform the test
Electrochemiluminescent Immunoassay (ECLIA)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If thyrotropin (TSH) is less than 0.3 mIU/L, then free T4 (FT4, thyroxine) will be performed at an additional charge.
If free T4 is normal and the TSH is less than 0.1 mIU/L, then T3 (triiodothyronine) will be performed at an additional charge.
If TSH is greater than 4.2 mIU/L, then free T4 will be performed at an additional charge.
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
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1.5 mL
Collection Instructions: Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
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 | |
| Ambient | 72 hours | ||
| Frozen | 30 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Monitoring patients diagnosed with thyroid disease
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
If thyrotropin (TSH) is less than 0.3 mIU/L, then free T4 (FT4, thyroxine) will be performed at an additional charge.
If free T4 is normal and the TSH is less than 0.1 mIU/L, then T3 (triiodothyronine) will be performed at an additional charge.
If TSH is greater than 4.2 mIU/L, then free T4 will be performed at an additional charge.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
This test utilizes a cascade testing approach to efficiently evaluate and monitor functional thyroid status.
The cascade begins with thyrotropin (TSH) 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 T4 (thyroxine) is performed. The supplemental measurement of free T4 in patients with abnormal TSH measurements allows one to better assess the severity of the changes.
Serum T3 (triiodothyronine) levels often are depressed in patients who are sick and hospitalized, 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 patients with hyperthyroidism, 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 free T4 concentrations.
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) 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.
Patients who are sick and hospitalized may have falsely-low or transiently-elevated TSH levels.
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/d.(1) In a study among 54 healthy volunteers, supplementation with 20 mg/d biotin resulted in a maximum serum biotin concentration of 355 ng/mL 1-hour postdose.(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 [HAMA]) 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. Peyro Saint Paul L, 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. TSH Reagent. Package insert. Roche Diagnostics; V2, 03/2020
4. Fatourechi V, Lankarani M, Schryver PG, 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;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
Method Description
Describes how the test is performed and provides a method-specific reference
The cobas e immunoassay thyrotropin (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: Elecsys TSH. Roche Diagnostics; V4.0, 02/2023)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
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.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
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.
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- Prospective clients should contact their account representative. 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.
CPT codes are provided by the performing laboratory.
84443
84439-(if appropriate)
84480-(if appropriate)
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| THCSM | Thyroid Cascade (Monitor), S | 11579-0 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| STSHM | TSH, Sensitive, S | 11579-0 |