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Thyroid function studies are used to delineate the presence or absence of hormonal abnormalities of the thyroid and pituitary glands. These abnormalities may be either primary or secondary and often but not always accompany clinically defined signs and symptoms indicative of thyroid dysfunction. Laboratory evaluation of thyroid function has become more scientifically defined. Tests can be done with increased specificity, thereby reducing the number of tests needed to diagnose and follow treatment of most thyroid disease. Measurements of serum sensitive thyroid-stimulating hormone (TSH) levels, complemented by determination of thyroid hormone levels [free thyroxine (FT-4) or total thyroxine (T4) with Triiodothyronine (T3) uptake] are used for diagnosis and follow-up of patients with thyroid disorders.
Additional tests may be necessary to evaluate certain complex diagnostic problems or on hospitalized patients, where many circumstances can skew tests results. When a test for total thyroxine (total T4 or T4 radioimmunoassay) or T3 uptake is performed, calculation of the free thyroxine index (FTI) is useful to correct for abnormal results for either total T4 or T3 uptake due to protein binding effects.
Measurement of Free Triiodothyronine (T3) and Reverse T3 is addressed in a separate policy.
The thyroglobulin test is primarily used as a tumor marker to evaluate the effectiveness of treatment for thyroid cancer and to monitor for recurrence. Not every thyroid cancer will produce thyroglobulin, but the most common types, papillary and follicular thyroid cancer, frequently do, resulting in increased levels of thyroglobulin in the blood. Thyroglobulin may be ordered, along with a TSH test, prior to thyroid cancer treatment to determine whether the cancer is producing thyroglobulin. The measurement of the protein thyroglobulin is an important laboratory test for checking whether a patient still has some thyroid present. The power of a serum thyroglobulin measurement lies in the fact that thyroglobulin can only be made by the thyroid gland (either the remaining normal part or the tumorous part). This means that when a patient has had their thyroid completely removed, the measurement of thyroglobulin in a blood sample can be used to check whether there is any tumor left behind.
A thyroglobulin antibody (TgAb) test is typically ordered along with the thyroglobulin test. Thyroglobulin antibodies are proteins produced by the body's immune system to attack thyroglobulin. These antibodies can develop at any time. When they are present, they bind to any thyroglobulin that may be present in the blood and interfere with the interpretation of the thyroglobulin test. Once they have developed, they will not go away and from that point forward will affect the usefulness of the thyroglobulin test.
Thyroid peroxidase (TPO, formerly known as the microsomal antibody) is primarily ordered to help diagnose an autoimmune thyroid disease and to distinguish it from other forms of thyroid dysfunction. It may be ordered to help investigate the cause of a goiter or other signs and symptoms associated with low or high thyroid hormone levels. Testing may be performed as a follow-up when other thyroid test results (such as T3, T4, and/or TSH) indicate thyroid dysfunction.
Routine measurement of antithyroid antibodies is not necessary for the assessment of thyroid function. However, a test for antithyroid peroxidase antibodies may be useful to predict the likelihood of progression to permanent overt hypothyroidism in patients with subclinical hypothyroidism.
Thyroid function testing may be considered medically necessary to:
Thyroid function testing may be medically necessary in patients with disease or neoplasm of the thyroid and other endocrine glands.
Thyroid function testing may also be medically necessary in patients with metabolic disorders; malnutrition; hyperlipidemia; certain types of anemia; psychosis and non-psychotic personality disorders; unexplained depression; ophthalmologic disorders; various cardiac arrhythmias; disorders of menstruation; skin conditions; myalgias; and a wide array of signs and symptoms, including alterations in consciousness; malaise; hypothermia; symptoms of the nervous and musculoskeletal system; skin and integumentary system; nutrition and metabolism; cardiovascular; and gastrointestinal system.
Thyroid testing may be considered medically necessary up to two times a calendar year in clinically stable, euthyroid patients.
More frequent thyroid testing may be considered medically necessary for patients whose thyroid therapy has been altered or in whom signs or symptoms of hyperthyroidism or hypothyroidism are present.
Follow-up thyroid testing may be considered medically necessary in patients with a personal history of malignant neoplasm of the endocrine system and patients on long term thyroid drug therapy.
Services performed outside the clinical indications contained in this Medical Policy will be considered not medically necessary.
The coverage guidelines outlined in this Medical Policy should not be used in lieu of the Member's specific benefit plan language.
3/26/2009: Approved by Medical Policy Advisory Committee (MPAC)
9/28/2009: Code reference section updated. New ICD-9 diagnosis codes 279.41, 279.49, 784.42, 784.43, 784.44, 784.51, 784.59 and 799.21, 799.22, 799.23 and 799.29 added to covered table. Added deleted statement to ICD-9 code 279.4, 784.5 and 799.2. Description revised for ICD-9 codes 784.49 and 793.99
12/01/2009: Policy Statement Section revised to define year as a calendar year for the statement, thyroid testing may be considered medically necessary up to two times a year in clinically stable patients.
01/15/2010: Typographical error corrected, changed V57.00 to V67.00
11/18/2010: Added the following ICD-9 codes to the Covered Codes table: 150.0 - 150.9, 151.0 - 151.9, 152.0 - 152.9, 153.0 - 153.9, 277.7, 530.0 - 530.9, 531.00 - 531.91, 532.00 - 532.91, 533.00 - 533.91, 534.00 - 534.91, 535.00 - 535.71, 555.0 - 555.9, 558.1 - 558.9, 560.0 - 560.9, 562.00 - 562.13, 564.00 - 564.9, 626.0 - 626.9, 780.2, 796.2, V10.03, V10.04, V10.05, and V10.43.
01/14/2011: Added ICD-9 codes 708.0 - 708.9 to the Covered Codes table.
01/24/2011: Added the following ICD-9 codes to the Covered Codes table: 627.0 - 627.9, 783.41, and 783.43.
02/23/2011: Added ICD-9 codes 346.00 - 346.93, 374.32, and 611.6 to the Covered Codes table.
05/09/2011: Added ICD-9 codes 259.0, 259.1, 314.00, and 314.01 to the Covered Codes table.
06/16/2011: Added ICD-9 codes 234.8, 194.0 - 194.9, and 227.0 - 227.9 to the Covered Codes table.
08/11/2011: Added ICD-9 codes 252.00 - 252.08 and 783.40 to the Covered Codes table.
12/13/2011: Added the following ICD-9 codes to the Covered Codes table: 268.9, 733.91, 611.1, 140.0 -165.9, 170.0 -176.9, 179 - 199.2, 200.00 - 208.98, 209.00 - 209.79, 230.0 - 234.9, and V10.0 - V10.91.
05/08/2012: Added 287.5, 374.55, and 567.82 to the Covered Codes table.
07/13/2012: Added 070.54, 274.00 - 274.9, 333.94, and 701.2 to the Covered Codes table.
10/01/2013: Policy title changed from "Thyroid Stimulating Hormone" to "Thyroid Studies." Policy description updated regarding thyroglobulin, thyroglobulin antibody, and thyroid peroxidase testing with references added to the Sources section. Added "euthyroid" to the policy statement regarding clinically stable patients. Added CPT codes 84432, 86376, and 86800 to the Code Reference section.
04/23/2014: Added ICD-9 codes V12.21 and V12.29 to the Code Reference section.
This may not be a comprehensive list of procedure codes applicable to this policy.
The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.