Dried blood spots: Clinical Utility

Use of dried blood spots (DBS) to screen newborns for inborn errors of metabolism (IEM) began as a pilot study in Hong Kong (HK) in 2015. Results from the pilot study showed the collective incidence of the 24 screened conditions to be 1 in 1,682. The pilot study demonstrated feasible logistics and a higher than previous estimation of 1 in 4,500 incidence of IEM in HK. Thus, upon completion of the pilot study, the HK government decided to extend the program in phases to all babies born in government hospitals. Universal implementation of metabolic newborn screening has only been made possible by usage of tandem mass spectrometry technology to process the DBS cards collected from newborn babies. The same technology can also be utilized and applied beyond the newborn period with some limitations. The rapid turnover time for important metabolic analytes makes it an attractive tool to frontline clinicians managing sick newborns and children while awaiting conventional confirmatory investigations. We present three cases in whom timely diagnosis of an IEM condition was made using DBS cards. We would like to raise awareness of physicians to the extended scope of using dried blood spots to diagnose IEM diseases beyond the newborn period.