[Evaluation of the detection of phenylketonuria and hypothyroidism at the Lille Regional Center].

During the past 20 years, neonatal screening for metabolic diseases has been developed and implemented in the Nord-Pas de Calais region. The regional centre (established in 1972) has screened more than 1,000,000 babies for phenylketonuria (PKU) and more than 700,000 for congenital hypothyroidism (CH). Ninety-two PKU and 182 CH patients were discovered and treated. The recent introduction of a computerised system for the clerical works in the centre has allowed a systematic survey of some parameters linked to the screening practices: collection, handling and follow-up of samples. The analysis of these parameters showed that 50% of samples were collected on the 5th day of life but 35% were collected after that date, and that 4.7% of specimen reached the laboratory 10 days or more after the day of collection. These delays can introduce a significant delay in the final diagnosis of affected children. The average age at which the diagnosis was suspected was 12.2 days in PKU and 20.6 days in CH. The difference was not only explained by the technical delay for TSH measurement but also by a later date of sampling. This observation suggests that, if blood collection was performed before nursery discharge, there were some pathologic factors justifying a later discharge. Of the control specimen (second test) which have been requested, 16% were not received; this represents a high risk of missing a case.