Factors Influencing Results for Thyroxine Concentration in Blood, as Measured in Paper Filter Spots in a Screening Program for Neonatal Hypothyroidism

standardmethod shows a correlationsthatisnot fully satis-factory,but the fact that thetwo methods arebasedon com-pletely different principles must be taken into account. Given the specificity of the immunological method, its more widespread usewould seem desirable. The method presented here is simpler and more rapid than traditional methods; perhaps further studies should lead to improvements