QUALITY ASSESSMENT OF URINARY ORGANIC-ACID ANALYSIS

The number of known inherited metabolic disorders resulting in an orga nic aciduria has increased steadily over the past two decades. Prompt and reliable detection is both clinically and technically demanding bu t is essential if appropriate treatment is to be undertaken. This is t he first study of laboratory performance in the detection of these dis orders to be undertaken in the UK. Some conditions were accurately ide ntified by most laboratories: for example for maple syrup urine diseas e, 12 of 14 laboratories provided an appropriate response and medium c hain acyl-CoA dehydrogenase deficiency was correctly identified by 15 of 17 laboratories. However, accuracy of detection was poorer for othe r conditions: for example, only eight of 17 laboratories detected tyro sinaemia type 1 and nine of 18 laboratories detected 4-hydroxybutyric aciduria. The strongest correlation with good performance was obtained by comparison with the extent of peak identification: r = 0.62, P = 0 .002. The need for regular attendance at scientific symposia was also supported by a weaker positive correlation with the average score achi eved, P = 0.08. Evidence also suggested that some of the laboratories with a low workload performed less well. No significant difference in performance could be demonstrated between the 17 laboratories who used gas chromatography-mass spectrometry and the six participants who use d gas chromatography alone.