A screening programme for congenital hypothyroidism: preliminary results.

Highly sensitive and precise radioimmunoassays for thyroxine (T4) and thyrotropin (TSH) in dried blood spots on filter paper cards have been developed and are used to screen newborn infants for congenital hypothyroidism. Blood spot TSH levels are measured in samples for which blood spot T4 levels fall in the lower 10 to 15 percent. There was a low recall rate of approximately one infant in every 550 screened. During a 17-month period 5225 infants have been screened for congenital hypothyroidism and two cretins have been detected. Due to very early diagnosis, both infants were commenced on T4 replacement therapy before the age of three weeks.