A thyroid uptake is a test performed to evaluate if your thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism) and by how much.  The procedure is carried out over the course of 2 days and is typically done with a nuclear medicine thyroid scan.


For a thyroid uptake, you may be required to be off any thyroid medications (Synthroid, Eltroxin, Tapazole, etc.) prior to the test.  You will be informed at the time of the booking whether to cease your medications and for how long.

You are also required to be fasting for 6 hours prior to your appointment and to remain fasting for 30 minutes after your appointment.



Captus 300 Uptake Probe
Equipment used for this test: Captus 300 Uptake Probe


Check-in at the Diagnostic Imaging Department at the Sault Area Hospital for your appointment.

A thyroid uptake is performed over the course of 2 days.  On the first day, you will be given a small pill containing a trace amount of radioactive iodine (Iodine-131).  You shouldn’t taste or feel anything different and reactions to the pill are extremely rare.  Once you have taken the pill you will be required to return the following day to evaluate how much of the iodine was taken into your thyroid over the 24 hour period.

To check how much of the radioactive iodine was taken into your thyroid over 24 hours we will be using an uptake probe.  The probe will initially be positioned over your thigh for a few minutes giving us a background for the amount of Iodine-131 in your body.  Next, the probe will be positioned against your neck for a few minutes to see how much of the Iodine-131 was taken up by your thyroid.  With the readings from your thigh and neck, we will be able to determine how over or underactive your thyroid is.

Following the uptake, it is common to have a thyroid scan to show whether the whole gland is over/underactive or whether it’s nodules (lumps and bumps) that are over/underactive.  Please see thyroid scan for more details.

Following your test, there are no restrictions and you will be able to drive as you normally would.  If you are planning on going into the United States of America you will set off the radiation detectors for approximately 1-2 weeks.  We can provide a letter explaining why you are setting off the detectors however you will still be stopped.

Once your scan is complete it will be examined by a radiologist and a report will be sent to the ordering doctor within a week.  Follow up your test with the ordering physician or your family doctor.

The Uptake Probe

The uptake probe we use for the thyroid uptake is a Captus 3000.  The probe is a long tube with a radiation detector in it that is position on the surface of the skin.  The probe doesn’t emit any radiation or sounds and is not a danger to anyone in the vicinity.