Primary congenital hypothyroidism (PCH) is currently detected effectively by heel-stick screening. When elevated thyrotropin (TSH) and/or decreased T4 are found in the blood of neonates, they are recalled, values are confirmed in venous blood and thyroxine replacement therapy (TRT) is immediately instituted, thus cretinism or severe retardation is prevented. However, in a significant percentage of neonates with abnormal blood levels of T4 or TSH, the disorder is transient. To help determine the

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... exact cause of PCH and the possibility of transient PCH, pinhole thyroid imaging is performed 30 min after an intravenous injection of 18.5 MBq (500 microCi) 99mTc-pertechnetate (TcPT). Patients with a nonvisualized gland or patients with images suggesting dyshormonogenesis are reevaluated at age 3-4 y to exclude transient PCH.