Coverage of thyroid function studies. (Featured CME Topic: Thyroid Dysfunction/Disease).

Thyroid function studies are used to delineate the presence or absence of hormonal abnormalities of the thyroid. These abnormalities may be either primary or secondary and usually accompany clinically well-defined signs and symptoms indicative of thyroid dysfunction. Serum levels of thyroid hormone are useful to confirm clinical hyperfunction, hypofunction or euthyroidism of the thyroid gland.

Thyroid function tests should not be performed without the presence of at least some supporting signs or symptoms of hyperthyroidism, hypothyroidism or thyroid mass (eg, tachycardia, bradycardia, tremor, fine or thick skin, sweating, weight changes, bowel changes, eyelid edema, exophthalmus, reflex changes, hearing loss, personality changes, swelling, thyroid masses, tenderness or prior abnormal thyroid function tests). Thyroid testing would be appropriate if thyroid disease is suspected, and there is an unexplained aspect of a patient's condition that could be accounted for by thyroid disease.

Laboratory analysis to detect 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. The American Thyroid Association recommends the measurement of serum sensitive thyroid-stimulating hormone (sTSH) levels complemented by an appropriate free thyroxine ([FT.sub.4]) estimate to represent the best and most efficient combination of blood tests for diagnosis and follow-up of most patients with thyroid disorders. This is true for most ambulatory patients. This recommendation is not to be used for certain complex diagnostic problems or on an inpatient basis, where many circumstances can skew test results.

Thyroid function levels do not determine the etiology of thyroid disease. Thyroid testing is reasonable and necessary to:

* distinguish between primary and secondary hypothyroidism;

* distinguish between primary and secondary hyperthyroidism;

* confirm or rule out primary hypothyroidism;

* confirm or rule out primary hyperthyroidism;

* monitor thyroid hormone levels; and

* monitor drug therapy in patients with primary hypothyroidism.

Thyroid function testing is medically necessary in patients with disease and neoplasm of the thyroid and other endocrine glands, metabolic disorders including malnutrition, hyperlipidemia, certain types of anemia, psychosis and nonpsychotic personality disorders, ophthalmologic disorders, various cardiac arrhythmias, disorders of menstruation, skin conditions, patients receiving amiodarone, and myalgias. Thyroid function testing is medically necessary as well in patients with 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. It is not medically necessary to perform follow-up thyroid testing in patients. with a personal history of malignant neoplasm of the endocrine system, or in patients on long-term drug therapy.

LIMITATIONS

Screening thyroid function studies are excluded by statute from Medicare coverage, and asymptomatic patients have not been shown to benefit from such screening. It may be periodically necessary to evaluate thyroid function in the symptomatic elderly, postpartum women 4 to 8 weeks after delivery, patients with autoimmune diseases, patients who have received previous radiation of the thyroid, and patients with previous thyroidectomy. Studies published on the efficacy of thyroid screening have demonstrated that the majority of patients found with previously undiagnosed thyroid disease were either symptomatic or had a clinically abnormal thyroid.

Testing may be covered up to two times a year in clinically stable patients. More frequent testing may be reasonable and necessary for patients whose thyroid therapy has been altered, or in whom symptoms or signs of hyperthyroidism are noted.

DOCUMENTATION REQUIREMENTS

The ordering physician must include evidence in the patient's clinical record that an evaluation of history and physical findings preceded the ordering of thyroid function tests. Documentation must show that signs and symptoms of thyroid disease were present to warrant the function testing or ongoing medical treatment where thyroid monitoring is appropriate. Office progress documentation must be submitted to Medicare upon request. When these tests are billed at a greater frequency than normal (two per year), the ordering physician's documentation must support the medical necessity of this frequency.

CODING GUIDELINES

* CPT codes for thyroid function studies are found in the Pathology and Laboratory sections of the CPT coding manual. Submit claims for a test listed with an appropriate ICD-9-CM code.

* Provide (for reporting purposes) codes that describe symptoms and signs, as opposed to diagnoses, when the physician has not established a diagnosis.

* Use a three-digit code if it is not further subdivided. Where fourth-digit and/or fifth-digit subclassifications are provided, they must be assigned. A code is invalid if it has not been coded to the full number of digits required for that code.

* Code (to the highest degree of certainty) and use diagnoses, such as signs, symptoms, abnormal test results, exposure to communicable disease or other reasons for the visit. Do not code diagnoses documented as "probable," "suspected," "questionable," "rule out" or "working diagnosis" as though they exist.

* Use ICD-9-CM code V58.69 when laboratory testing is performed solely to monitor response to medication.

* Code from the V67 category a periodic follow-up encounter for laboratory testing in patients with prior history of disease, who are no longer under treatment for the condition.

* Code and sequence ahead of the manifestation the underlying condition, according to the ICD-9-CM coding conventions (codes that appear in italics are considered manifestation codes). For example, the diagnosis statement-thyrotoxic exophthalmos (376.21)-appearing in italics in the tabular listing, requires the thyroid disorder (242.0-242.9) be coded and sequenced ahead of thyrotoxic exophthalmos. Therefore, a diagnostic statement listed as a manifestation in the ICD-9-CM book must be expanded to include the underlying disease to accurately code the condition.

Reference

(1.) Thyroid Testing Local Medical Review Policies from Georgia, Maryland, North Carolina, Tennessee, Texas and Virginia.

From the Department of Practice Management Services, SMA Services, Inc., a subsidiary of Southern Medical Association, 35 Lakeshore Dr, P0 Box 190088, Birmingham, AL 352 19-0088.