The uptake (RAIU) is crucial for evaluating how well does the thyroid gland function. Measuring the amount of radioactive iodine in the gland allows the physician to evaluate how well thyroid hormones are produced considering radioactive and dietary iodine are similarly processed by the gland. The thyroid scan is requested for evaluating the abnormalities found in both physical examinations “neck mass or swelling in addition to signs and symptoms of hyper or hypothyroidism" and lab examinations abnormal TSH, T3, or T4 values. Fasting: Is not preferred as you will be requested to considerably increase fluid intake. Medication contradiction: Anti-thyroid drugs should be stopped for at least 5 days, T3 (Cytomel) should be stopped for 2 weeks and T4 (Thyroxin) should be stopped for 4 weeks depending on the daily dosage Any drugs, supplements, foods or salts containing iodine should be stopped for at least 1 week Drugs such as adrenocorticotropic hormone (ACTH), barbiturates, corticosteroids, estrogen, lithium, Lugol’s solution, nitrates, phenothiazines, and tolbutamide should be stopped for 1 week In addition to the above for RAIU, imaging with iodinated contrast should be avoided. In case it was already done the study should be delayed for at least 4 weeks Tracer Method of Intake: For thyroid scan: the tracer will be intravenously injected. For the Uptake measurement: the liquid or capsule radioactive iodine will be ingested. Examination duration: The imaging process will take up to 10 minutes. Imaging will be conducted 20 minutes after the injection. As for RAIU measurements are conducted 5 hours following the radioactive iodine ingestion and again in 24 hours. Additional related examinations: Additional imaging maybe required depending on the examination outcome.