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A person with a lump in the neck will lead the doctor to suspect a problem with the thyroid gland. The doctor may ask you questions about other possible symptoms that you could be experiencing at the time. They will then feel the area of the neck where the lump is and if they suspect that the thyroid is involved they will order some tests to confirm this. The majority of these nodules are benign thyroid nodules or cysts.

Non-laboratory tests

Ultrasound: Most neck lumps will be investigated with the use of ultrasound. This imaging technique allows doctors to assess the location and characteristics of the lump, which includes size, mass and calcium deposits to help decide whether it is benign or cancer. Ultrasound may also be used to detect whether MTC has spread to local lymph nodes. Other causes of thyroid lumps which  include papillary thyroid cancer and multi nodular goitre, can also be assessed with this technique.

Laboratory tests

Fine needle aspiration: Often a sample of the lump is taken while the doctor is viewing the lump by ultrasound. This small amount of tissue can give an indication of whether or not the lump is cancer and has a high degree of sensitivity especially including special staining methods for diagnosis.

Calcitonin: this is a hormone produced by the C-cells in the thyroid gland. In cases of medullary thyroid cancer it will often be raised. Calcitonin levels, as well as a calcitonin stimulation test may be ordered to confirm MTC.

In addition to aiding diagnosis of MTC, the blood test for this hormone may be used for monitoring treatment and recurrence of MTC. With successful treatment, calcitonin levels will usually fall to very low levels. If, after successful treatment, calcitonin levels begin to rise, then it is likely that there is a recurrence of medullary thyroid cancer.
Calcitonin Stimulation tests- more sensitive than calcitonin measurements alone. This involves collecting a baseline sample, then giving the patient an injection of intravenous calcium or less commonly, pentagastrin, to stimulate calcitonin production. Several more blood samples are then collected over the next few minutes to gauge the effect of the stimulation. Patients with early C-cell hyperplasia and/or MTC will usually have very significant increases in their levels of calcitonin during this test.

Thyroid function tests: These are one of the first tests ordered when a doctor suspects a problem with your thyroid. It includes TSH, FT4 and FT3 and provides information about how your thyroid in functioning.

Carcinoembryonic antigen (CEA)- this antigen is often elevated in people with MTC. Malignant transformed C cells- may produce and secrete (CEA).

Genetic testing: Due to the high percentage of inherited MTC, doctors may advise that a genetic test be performed. The presence of the RET oncogene indicates an inheritable form of the cancer and will guide investigation of family members. 

Last Review Date: September 7, 2019