How long does a thyroid scan test take?

Varies. A thyroid uptake and scan may be done with different isotopes and protocols resulting in scan time variation. Typically is done with i-123; you take the capsule one day and you come back the next day at 24 hr for a neck scan that takes aprox 15-20 minutes. In certain circumstances some places do this scan at 4-6 hours after you take the capsule.
Depends. 60 to 90 minutes should be enough. If radioactive iodine is used, about 15 minutes will be needed for measuring thyroid gland uptake. Imaging time will depend on how much radioactivity was concentrated by the thyroid. 20 to 40 minutes for imaging would be reasonable. If intravenous radiotracer (pertechnetate) is used instead of radioactive iodine, the process lakes shorter about of time.
Depends. The thyroid scan using tc99m pertechnetate is completed within about an hour. The scan utilizing radioiodine can take a day or so since you may need to take the pill a day before getting scanned. Sometimes you will need to come back again to get re-imaged if you are getting a post-therapy cancer scan.