Pediatric Risk of Hypothyroidism With Iodinated Contrast Media

Inclusion Criteria: * Male and female patients aged birth to 3 years who, as part of the standard of care in the clinical practice of medicine, are referred to and will undergo a radiographic diagnostic imaging procedure that uses intravascularly administered iohexol (Omnipaque™), iodixanol (Visipaque™), iopromide (Ultravist®), or ioversol (Optiray®) as the ICM for contrast enhancement. * Written informed consent has been given for the patient by one or more parents or other legally acceptable representatives, as required by local regulations and laws. * When applicable (neonates), the patient's biological mother consents to providing information about her medical history and medication usage. * The patient has normal pre-procedure (screening) serum TFTs (TSH, TT4, FT4, TT3), TSI, and urine (UI/UCr). * The patient's pre-procedure (screening) serum chemistry is either normal or not clinically significantly abnormal. * The patient has normal pre-procedure (screening) eGFR for age by the revised Schwartz formula \[Schwartz et al 2009\]. * The patient's parent(s) or other legally acceptable representative(s) is/are able and willing to comply with the study schedule and procedures. Exclusion Criteria: * The planned radiographic procedure is part of a clinical research study rather than clinical practice. * The patient has known or suspected thyroid disease, Down syndrome (trisomy 21), or Type 1 diabetes. * The patient currently receives thyroid hormone replacement therapy, or such therapy is planned or being considered. * The patient has been exposed to thyroid protection for imaging procedures, within the last 6 months or such procedure is planned or being considered. * The patient currently receives one or more anti-thyroid medications, or such therapy is planned or being considered. * The patient has known or suspected past or present exposure to thyroid suppressants, including but not limited to drugs (e.g., amiodarone), inorganic iodide (potassium iodide, sodium iodide, etc.), perchlorate, thiocyanate, nitrate, lithium, and topical iodine disinfectant (e.g., povidone-iodine). * The patient has undergone (or is expected to undergo during the study) radiation treatments to the head or neck. * There is a high likelihood that the patient will undergo surgery or more than one ICM-enhanced procedure in the following 10 weeks. * The patient has a history of hypersensitivity to ICM or any components, or a history of a severe cutaneous adverse reaction to ICM.