Newborn screening programs play a vital role in improving the lifestyle of an individual by reducing the morbidity and mortality rate. In most developed countries, it is an essential program carried out on all neonates. Many measures have been taken to improve NBS programs due to advancement in many of the analytical techniques. In this review advancement in techniques to detect Phenylketonuria (PKU) is studied. Over the years many assays such as colorimetry, Guthrie's test, fluorometry, chromatography, mass spectrometry and tandem mass spectrometry (MS/MS) have been evolved. And those did prove to help detect Phe and Try. However, ESI-MS/MS was studied to be the most sensitive and specific technique when in comparison to the other mass spectrometric techniques. As it has a LOQ and LOD of phe and tyr of 0.0015 and 0.0045µmol/L; 0.0025 and 0.007 µmol/L respectively. In future, newer approaches will enhance the detection and treatment of newborns affected by PKU and other inborn errors of metabolism.
