Understanding your Blood Test Results
The thyroid cancer specialist managing your care will order blood work several times during the course of your treatment and in the months and years following. As you will be on a synthetic form of thyroid hormone for the rest of your life, it is important to continually gauge whether the dose you are on is creating the desired effect in your body. You and your physician will work towards finding the correct dosage for you, and you will likely remain on it for long periods of time. Weight gain or loss, pregnancy and menopause are some events that may affect your dosage.
After the first year post-surgery, your doctor may order blood tests on a yearly or bi-yearly basis. There are three main blood tests that will be monitored:
- Thyroid Stimulating Hormone (TSH): Once your thyroid has been removed TSH is regularly monitored. As the presence of TSH may stimulate the growth of thyroid cancer cells, it is important for thyroid cancer survivors to be given enough thyroid hormone replacement to keep the TSH level lower than normal.
- Patients at low risk for thyroid cancer recurrence may be allowed a TSH in the range of .1 - .5 mIU/L. All other patients may be required to keep their TSH as suppressed as they comfortably can (0.1 mIU/L or less). The recommended target TSH level needs to be identified per patient and will depend on a number of factors that your doctor will need to take into consideration. Adjustment to the dose of hormone replacement (i.e. T4 - Synthroid or Eltroxin) helps to achieve the desired TSH level. Raising the dose of hormone replacement has the effect of lowering the TSH.
- Thyrogobulin (Tg): Thyrogobulin is the "cancer marker" for thyroid cancer. As such, this number should be as low as possible (sometimes expressed as "undetectable"). It may take several months (even years) for the measure to come down to the desired level following surgery and if need be, RAI treatment.
- Anti-thyrogobulin anti-bodies (TgAb): Some patients produce anti-bodies which, while not harmful, mask the reliability of the Tg value. Sometimes the anti-bodies disappear over time and that is a valuable secondary sign that all cancer has been eliminated.
As well, some patients (especially those with parathyroid loss or damage) will have their blood calcium levels periodically measured.
Disclaimer: The information contained on this website does not constitute medical advice. Visitors are encouraged to work closely with their doctors to make sure that their individual medical needs are met. The Canadian Thyroid Cancer Support Group (Thry'vors) Inc. does not endorse any product, treatment, service or practitioner and is not responsible for the quality of the information or services offered by other organizations or websites.
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