Thyroid Cascade Profile

TEST: 330015
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CPT: 84443. If reflex testing is performed, concomitant CPT codes/charges will apply.
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Test Includes

Thyroid-stimulating hormone (TSH) with automatic reflex (as diagnostically warranted) to free thyroxine, free triiodothyronine, and/or thyroid peroxidase (TPO) antibodies. If reflex testing is performed, additional charges/CPT code(s) may apply.

Special Instructions

Note: Special reflexing. If TSH is <0.450, it will reflex to thyroxine (T4), free, direct and depending on the thyroxine (T4), free, direct result, may reflex to a triiodothyronine (T3), free, both at an additional charge. If the TSH is >4.500, it will reflex to thyroxine (T4), free, direct and depending on the thyroxine (T4), free, direct result, may reflex to a thyroid peroxidase (TPO) antibody, both at an additional charge.

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

Expected Turnaround Time

Within 1 day

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

For more information, please view the literature below.

Thyroid Testing: Assessing Thyroid Disease in Your Patients

Thyroid Cascade Testing: Differential Laboratory Diagnosis of Thyroid Function

Specimen Requirements

Specimen

Serum (preferred) or plasma

Volume

2 mL

Minimum Volume

1 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.

Collection

If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.

Storage Instructions

Room temperature

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3

Causes for Rejection

Plasma specimen

Test Details

Use

Aid clinicians in obtaining an appropriate diagnosis for common adult thyroid disorders. The cascade begins with a third-generation thyroid-stimulating hormone (TSH) test. If the TSH result is normal, a euthyroid status is assumed and testing stops. Additional testing is performed only if the initial TSH result is abnormally high or low. The cascade algorithm will select specific tests, based on the results of previously performed tests, which are necessary to arrive at the most appropriate laboratory diagnosis. The assayed value of a test, relative to the reference interval of that specific test, determines which, if any, additional tests are performed. The cascade proceeds, selecting specific tests, until the most probable diagnosis can be made.

Limitations

This profile is not intended for use in pediatric patients or in monitoring patients receiving treatment for thyroid disease with either ablative or suppressive therapy. It would also not be appropriate to use this procedure to diagnose primary thyroid neoplasm.

Methodology

Electrochemiluminescence immunoassay (ECLIA)

References

Davey R. Thyroxine, thyrotropin, and age in a euthyroid hospital patient population. Clin Chem. 1997 Nov; 43(11):2143-2148. 9365400
Davey RX, Clarke MI, Webster AR. Thyroid function testing based on assay of thyroid stimulating hormone: Assessing an algorithm's reliability. Med J Aust. 1996 Mar 18; 164(6):329-332. 8606655
Feldkamp CS, Carey JL. An algorithmic approach to thyroid function testing in a managed care setting. 3-year experience. Am J Clin Pathol. 1996 Jan; 105(1):11-16. 8561076
Klee GG, Hay ID. Role of thyrotropin measurements in the diagnosis and management of thyroid disease. Clin Lab Med. 1993 Sep; 13(3):673-682. 8222581
Ladenson PW, Singer PA, Ain KB, et al. American Thyroid Association guidelines for detection of thyroid dysfunction. Arch Intern Med. 2000 Jun 12; 160(11):1573-1575.10847249

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
330015 Thyroid Cascade Profile 004261 TSH uIU/mL 11580-8
Reflex Table for TSH
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 001976 Thyroxine (T4) Free, Direct, S 019746 T4,Free (Direct) ng/dL 3024-7
Reflex 2 010390 T3Free 010392 Triiodothyronine (T3), Free pg/mL 3051-0
Reflex Table for TSH
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 001976 Thyroxine (T4) Free, Direct, S 019746 T4,Free (Direct) ng/dL 3024-7
Reflex 2 010390 T3Free 010391 Interpretive Comment N/A
Reflex Table for TSH
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 001977 Thyroxine (T4) Free, Direct, S 019747 T4,Free (Direct) ng/dL 3024-7
Reflex 2 330018 Thyroid Peroxidase (TPO) Ab 006677 Thyroid Peroxidase (TPO) Ab IU/mL 8099-4
Reflex Table for TSH
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 001977 Thyroxine (T4) Free, Direct, S 019747 T4,Free (Direct) ng/dL 3024-7
Reflex 2 330018 Thyroid Peroxidase (TPO) Ab 330017 Interpretive Comment N/A

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