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Radiology Coding Alert

Matrix of Variables Governs Use of Thyroid Scan Codes

Published on Wed Aug 01, 2001

Nuclear medicine procedures are often used to diagnose and treat an array of thyroid diseases, ranging from Graves disease to hypothyroidism to thyroid carcinomas. Coders must sort through a matrix of variables, notes Cindy Parman, CPC, CPC-H, co-owner of Coding Strategies Inc., an Atlanta-based firm that supports 1,000 radiologists and 350 physicians from other specialties.
 
Coders must distinguish between multiple diagnostic and therapeutic services to ensure correct coding and receive proper reimbursement. "It's particularly important to understand the differences between imaging and uptake before reporting a specific code," she says.
 
Note: The table on page 60, "Checklist for Diagnostic Thyroid Scans," can help coders sort through the elements that determine which code to assign.

Diagnostic Thyroid Studies
 
Code series 78000-78020 represents diagnostic studies of the thyroid used to evaluate thyroid function, identify congenital abnormalities, assess palpable nodules and detect thyroid cancer. Among the diagnosis codes that support these scans are 784.2 (swelling, mass, or lump in head and neck), 240.9 (goiter, unspecified, enlargement of thyroid), ICD-9 783.2 (abnormal loss of weight), 785.0 (tachycardia, unspecified) and 785.1 (palpitations).
 
During an uptake procedure, the nuclear radiologist administers an oral dose of radioactive iodine or injects 99mTc pertechnetate. The physician measures radiation levels in the thyroid at various times, beginning as early as 20 minutes after administration, up to 24 hours later. "Thyroid uptake produces a numerical value that helps the nuclear radiologist detect and quantify the effects of thyroid disease," Parman explains.
 
Imaging studies, on the other hand, allow the physician to evaluate the location, size and morphology of the thyroid. In some cases, patients receive an intravenous injection of the radiopharmaceutical (RP), with images taken 20 or 40 minutes later. In other cases, the RP is administered orally and images are obtained at six and/or 24 hours.  
 
For either type of scan, coders must also ascertain if  single or multiple determinations were made. Within the diagnostic series, 78006 (thyroid imaging, with uptake; single determination) is most often assigned and represents a procedure with both components, explains Donna Richmond, CPC, radiology coding specialist with Acadiana Computer Systems Inc., a medical billing management company based in Lafayette, La., that serves more than 200 radiologists, pathologists and anesthesiologists. "This is assigned when the physician measures the uptake once and obtains images," Richmond says.
 
If images and multiple uptake measurements are taken, CPT 78007 (... multiple determinations) should be assigned. "In this case, the nuclear radiologist is measuring the levels of radioactivity two or more times, perhaps at six, 12 and 24 hours following administration of the drug," she says. "This type of study is conducted, for instance, in cases of possible hypothyroidism. The physician is checking the functionality of the thyroid and may not see any results after six hours. He or she will go back at six hours and check the uptake again, and possibly repeat it even later."
 
Less common are uptake studies without imaging, which are reported with 78000 (thyroid uptake; single determination) or 78001 (... multiple determinations). Also, 78003 (... stimulation, suppression or discharge [not including initial uptake studies]) is assigned for tests that identify abnormalities of the thyroid by measuring its function when specific substances are administered to stimulate or suppress activity.
 
Likewise, 78010 (thyroid imaging; only) is reported on those rare occasions when only a visual evaluation is conducted. A second imaging study is reported with 78011 (... with vascular flow) and may be used when thyroid cancer is suspected. "This study allows the physician to visualize how the blood flows through the gland," Parman says. "Tumors create their own vascular network, and if nuclear radiologists identify increased blood flow to that area, they may be able to diagnose and localize the growth."
 
Vascular imaging, she adds, produces dynamic images (i.e., visualization of the movement of blood entering, passing through and exiting the thyroid), whereas the other imaging studies are static.

Scans Following Cancer Diagnosis
 
Four of the diagnostic thyroid codes are used exclusively after cancer has been found (e.g., 193, malignant neoplasm of thyroid gland) and the patient has been treated, usually with surgery and/or ablation of the thyroid. These codes help physicians identify metastases. Three of the codes describe imaging only, while the fourth (an add-on code) is used for uptake studies.
 
"These codes are used to determine if a thyroid cancer has migrated to other parts of the body," Parman explains. "Thyroid is nearly always a primary cancer. Early forms can be treated quite successfully. But if the cancer is advanced or aggressive, it can metastasize quickly." And, the studies can be performed on residual thyroid tissue after excision to ensure that no cancer cells remain.
 
Code 78015 (thyroid carcinoma metastases imaging; limited area [e.g., neck and chest only]) describes a limited study, while 78018 is used to report a whole body scan. Code 78016 (... with additional studies [e.g., urinary recovery]) is used to report other evaluations in addition to imaging.
 
In 1999, CPT supplemented these three codes with +78020 (thyroid carcinoma metastases uptake [list separately in addition to code for primary procedure]), to be used with 78018 only. Because 78020 is an add-on code, modifier -51 (multiple procedures) need not be appended. Code 78020 reflects the work performed to measure the uptake in metastastic lesions remote from the thyroid bed, which are most commonly in the lung.
 
When reporting any of these diagnostic studies in an independent diagnostic testing facility (IDTF) or physician's office to private payers, coders should also report the RP with 78990 (provision of diagnostic radiopharmaceutical[s]). "CPT provides a specific code for reimbursement of the radioactive materials," Richmond points out. "Too often, coders overlook the fact that they may assign this code, too." When submitting claims for services provided to Medicare beneficiaries, assign HCPCS codes describing the specific drugs and supplies used (e.g., A9500, supply of radiopharmaceutical diagnostic imaging agent, technetium Tc 99m sestamibi, per dose).

Coding Therapeutic Services for Thyroid Disease
 

Codes for the treatment of various thyroid conditions (79000-79035) are relatively straightforward, Parman says. Codes 79000 (radiopharmaceutical therapy, hyper-thyroidism; initial, including evaluation of patient) and 79001 (... subsequent, each therapy) describe procedures to ablate the thyroid, often to treat Graves disease (242.00, thyrotoxicosis with or without goiter; without mention of thyrotoxic crisis or storm).

"Coders should note that 79000 includes an office visit with the patient," she adds. "E/M services are often provided at the onset of treatment but are bundled into the procedure code when performed on the same day."

In some patients, overactivity of the thyroid gland produces cardiac symptoms, and the nuclear radiologist will arrest thyroid secretions to stop damage to the heart. This therapy is described in 79020 (radiopharmaceutical therapy, thyroid suppression [euthyroid cardiac disease], including evaluation of patient) and also includes an E/M service.

The two remaining codes are used to report cancer treatments. Code 79030 (radiopharmaceutical ablation of gland for thyroid carcinoma) is used when the nuclear radiologist administers an oral dose of iodine-131 sodium iodide to destroy the function of the thyroid gland and purposely cause hypothyroidism, Parman explains. Similarly, 79035 (radiopharmaceutical therapy for metastases of thyroid carcinoma) is assigned when the same substance is used to destroy cancer cells that have metastasized from the thyroid.

As with the diagnostic codes, nuclear radiology practices may report a distinct code for RPs used. When RPs are administered for treatment, 79900 (provision of therapeutic radiopharmaceutical[s]) or the appropriate Level II HCPCS codes should be billed.

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