Newborn Screening for Phenylketonuria

Newborn screening (NBS) for phenylketonuria in Latin America gave its first step in an organized way 3 decades ago when the first national NBS program was implemented in Cuba. From then onward, it experienced a slow but continuous growing, being currently possible to find from countries where no NBS activity is known to several countries with consolidated NBS programs. This complex scenario gave rise to a great diversity in the criteria used for sample collection, selection of analytical methods, and definition of cutoff values. Considering this context, a consensus meeting was held in order to unify such criteria, focusing the discussion in the following aspects—recommended blood specimens and sample collection time; influence of early discharge, fasting, parenteral nutrition, blood transfusions, extracorporeal life support, and antibiotics; main causes of transient hyperphenylalaninemias; required characteristics for methods used in phenylalanine measurement; and finally, criteria to define the more appropriate cutoff values