Thyroid Disease (cont.)
How is the diagnosis of thyroid disease made?
Blood tests
Blood tests are often used to help determine thyroid function. Thyroid
stimulating hormone (TSH) is often a screening tool and can be used along with
serum T3 and T4 levels. If these hormones are abnormal, and further information
regarding a possible cause is needed, antibody levels in the blood can be
checked. Depending on the clinical situation, your doctor may look for specific
antibodies such as:
Imaging
If there is concern about the structure of the gland, if
size needs to be quantified or if there is a suspicion of cancer, imaging tests
may be performed. Common modes of imaging include an ultrasound of the thyroid gland and
radioiodine scanning
and uptake. The ultrasound helps show size and consistency of the gland (for
example, it is good at detecting cysts or calcifications within a gland), but it
cannot always tell a benign gland from a cancerous gland. Ultrasounds may be
done in a doctor's office or in a hospital Radiology
department.
Thyroid scans involve the use radioactively labeled form
of iodine and are usually performed the Radiology department of a hospital or
clinic. Since the thyroid is the only tissue in the human body that picks up
iodine, the scan is
very specific for finding thyroid tissue. If the thyroid is not picking up
iodine normally, "spots" show up on the scan. A "cold" spot implies that the
tissue is not picking up enough iodine compared to the rest of the gland. This
may be seen in nonfunctioning nodules and may also be a sign of malignancy.
A
"hot" spot implies that the tissues in that area is taking up more iodine than
the surrounding tissue, and is overactive. This may be seen in a toxic nodule.
Hot spots are rarely ever cancerous. In addition, there are comparison values to
determine what normal thyroid uptake should be. A normal thyroid picks up 8%-35%
of the administered dose of iodine within 24 hours. If values above or below
this range is seen, it may point to underlying thyroid disease.
Biopsy
A biopsy provides a tissue sample for a pathologist to look at. This is
usually the gold standard, especially when looking for diseases such as cancer.
Thyroid biopsies are usually performed using a
fine need to aspirate cells from the
gland. This is often referred to as fine needle aspirate or an FNA. FNAs can be
done in a doctor's office or in a clinic setting, and may involve an ultrasound
machine to help guide the needle. Tissue samples can also be obtained during
surgery. An FNA is a safe easily performed procedure, however, depending on the
skill of the person performing the procedure, there is a chance that the
aspiration may not yield enough tissue, or that the sampling is not of the right
area.
Next: What is the treatment for thyroid disease? »
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