SCINTIGRAM . This technique uses a special camera to produce a brightly multicoloured picture showing where iodine is taken up by thyroid tissue, and how vigorously. Like the RAIU test, it depends on having a measured amount of the weak radioiodine,123I, or technetium 99m first. In a few centres fluorescent scanning is available: this measures ordinary, non-radioactive iodine through something like an X-ray, and almost no radiation is involved.
This test is useful:
- To show the size and shape of the gland.
- To check for thyroid tissue behind the breastbone.
- To find out whether a lump in the tongue or neck is thyroid tissue that has gone off course during development.
- Most importantly, to provide information on a particular knob or lump of tissue in the thyroid.
- a 'hot' nodule (showing as red) is overactive, taking in a lot of iodine;
- a 'warm' nodule (showing as orangey-yellow) is normally active;
- a 'cold' nodule (showing as greenish) is not taking up iodine and may be a cyst or a tumour. This calls for further investigation, to exclude cancer.
X-RAY . An ordinary X-ray gives a shadowy idea of the size and position of the thyroid. In particular, a chest X-ray may reveal a shadow, behind the breastbone, which could be an extension of thyroid tissue. Ultrasound, a CY scan or a scintigram will be needed for more precise information.
BARIUM SWALLOW This is an X-ray taken while you are swallowing a barium drink that shows up on X-ray. It reveals any pressure on your gullet.
CT (COMPUTERISED TOMOGRAPHY) SCAN . This is an X-ray that presents what looks like pictures of slices through the next or other area.
ULTRASOUND . This is a simple painless method of obtaining a picture of an ionternal organ, including the thyroid. It produces an on-going picture by processing the echo of a high-frequency sound projected on to the organ. Apart from distinguishing a cyst from solid tissue, the ultrasound provides an ongoing image of the organs and structures in your neck. This is invaluable for guiding the needle when a biopsy of a particular part of the thyroid is required.
FINE NEEDLE ASPIRATION. This is a neat method of doing a biopsy to obtain a sample of tissue to examine under the microscope and identify precisely. The great value of FNA is for distinguishing between a commonplace nodule of normal thyroid tissue, a harmless cyst or benign growth and a cancer. This knowledge is a signpost to the best form of treatment.
METABOLIC RATE. Although the main work of the thyroid is controlling the rate at which the bodily processes use up the available nourishment, the metabolic rate is seldom tested. A raise background or basic metabolic rate goes with over-activity of the thyroid, and accounts for the person who eats enormously and stays thin. The opposite happens with an under-active thyroid.
ELECTROCARDIOGRAPH . This electrical tracing of the heart's activity is the standard method of assessing how well the heart is working. It shows characteristic changes in overactive and underactive thyroid.
OPTHALMIC CURVE METER. This apparatus measures the degree of protrusion of the eye or eyes.
JKL's "NORMAL2 LAB VALUES GUIDE .
Clinical Chemistry, Toxicology, Seriology - reprinted from health Reference - 2001