Text Box: SCREENING FOR INBORN ERRORS OF METABOLISM WITH TANDEM MS: RESULTS OF ONE YEAR¡¯S SURVEY Hasanoğlu A, T¨¹mer L, Biberoğlu G, Ezg¨¹ FS Gazi University Department of Pediatrics, Division of Pediatric Metabolism and Nutrition, Ankara, Turkey Objective: The determination of aminoacid and acylcarnitine profiles from blood spots on Guthrie cards with Tandem MS for the screening of inborn errors of metabolism is a very important diagnostic tool. By the progression in sampling and data interpretation, tandem MS has become a screening method not only for risky population but for all newborns. Methods: All the patients in the Newborn Unit as well as the newborns those are carrying a risk for inborn errors of metabolism have been being screened with tandem mass spectrometry for about one year in Gazi University Hospital. Results: Among the risky newborns two were diagnosed to have propionic acidemia and four were diagnosed to have phenylketonuria whereas no metabolic disease was diagnosed among the patients in the Newborn Unit. Conclusion: It could easily be guessed that the number of patients those have inborn errors of metabolism would increase when the use of tandem mass spectrometry becomes prevalent in screening. 1124