Thyroid cancer diagnosis
- thyroid biopsy showing
anaplastic, follicular, medullary or papillary carcinoma cells
- ultrasound of the thyroid revealing nodule
- thyroid scan showing cold
nodule (a nodule that does not light up on scan)
- laryngoscopy showing paralyzed
vocal cords
- serum calcitonin (for
medullary cancer) or serum thyroglobulin (for papillary or follicular cancer), elevated
A thyroid cancer diagnosis may also look for altered results of the following
tests:
More detailed information about Thyroid cancer diagnosis
The doctor may use several tests to confirm a diagnosis of thyroid cancer. The size and
location of the lump has to be identified and it has to be determined whether the lump is
non-cancerous (benign) or cancerous (malignant). Blood tests, such as the thyroid
stimulating hormone (TSH) test, may be ordered to check how well the patient's thyroid is
functioning.
A test known as the calcitonin test may be ordered if medullary thyroid cancer is
suspected. Calcitonin is a hormone produced by the C cells (also called the parafollicular
cells) of the thyroid gland, in response to rising levels of calcium in the blood. This
hormone lowers calcium levels in blood serum by slowing the rate at which the bones absorb
it and increasing the rate at which the kidneys discharge it. When the parafollicular
cells of the thyroid become cancerous, they produce too much calcitonin. Because increased
serum levels of the calcitonin hormone are characteristic of medullary thyroid cancer, the
calcitonin test, which measures serum levels of calcitonin, can be used to confirm a
diagnosis of medullary thyroid cancer.
Imaging tests such, as a computed tomography scan (CT scan) or an ultrasound scan, may
be used to produce a picture of the thyroid. In ultrasonography, high-frequency sound
waves are bounced off the thyroid. The pattern of echoes that is produced by these waves
is converted into an image by a computer. This test can determine whether the lumps found
in the thyroid are fluid-filled cysts or solid malignant tumors.
A radioactive scan can be used to identify any abnormal areas in the thyroid. The
patient is given a very small amount of radioactive iodine, which can either be taken by
mouth or injected into the thyroid. Since the thyroid is the only gland in the body that
absorbs iodine, the radioactive iodine accumulates there. A x-ray image can then be taken
or an instrument called a "scanner" can be used to identify areas in the thyroid
that do not absorb iodine normally. These abnormal spots are called "cold spots"
and further tests are performed to check whether the cold spots are benign or malignant
tumors. If a significant amount of radioactive iodine is concentrated in the nodule, then
it is termed "hot" and is usually benign. |