The<unk>  is a type of scan used in the diagnosis of thyroid problems, particularly hyperthyroidism. It is entirely different from<unk><unk>  therapy (RAI therapy), which uses much higher doses to destroy cancerous cells. The RAIU<unk>  is also used as a follow up to RAI therapy to verify that no thyroid cells survived, which could still be cancerous. The patient swallows a radioisotope of<unk>  in the form of capsule or fluid, and the absorption<unk>  of this radiotracer by the thyroid is studied after 4–6 hours and after 24 hours with the aid of a scintillation counter. The dose is typically 0.15–0.37 MBq (4–10 μCi) of 131I<unk> , or 3.7–7.4 MBq (100–200 μCi) of 123I<unk> . The RAIU<unk>  is a reliable measurement when using a dedicated probe with a reproducibility of 1 percent and a 95%-least-significant-change of 3 percent. The normal<unk>  is between 15 and 25 percent, but this may be forced down if, in the meantime, the patient has eaten foods high in<unk> , such as dairy products and seafood. Low<unk>  suggests thyroiditis, high<unk>  suggests Graves' disease, and unevenness in<unk>  suggests the presence of a nodule. 123I has a shorter half-life than 131I (a half day vs. 8.1 days), so use of 123I exposes the body to less radiation, at the expense of less time to evaluate delayed scan images. Furthermore, 123I emits gamma radiation, while 131I emits gamma and beta radiation.
Radioactive iodine uptake test
ACTH stimulation test
Thyroidectomy
Thyroid hormone binding ratio
Sestamibi parathyroid scan
Combined rapid anterior pituitary evaluation panel
Thyroid Feedback Quantile-based Index
Hypophysectomy