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J Lab Med Qual Assur. 2018 Sep;40(3):149-154. Korean. Original Article. https://doi.org/10.15263/jlmqa.2018.40.3.149
Jun SH , Seo JD , Lee K , Song J .
Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. Songjhcp@snu.ac.kr
Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea.
Abstract

Background

Newborn screening of tyrosinemia type 1 is important for identifying infants at risk for developing this disease before life-threatening symptoms occur. It is difficult to differentiate between tyrosinemia type 1 and transient neonatal tyrosinemia (TNT) by analyzing tyrosine alone. Thus, succinylacetone must be analyzed. In this study, we measured succinylacetone in dried blood spot (DBS) by HPLC-tandem mass spectrometry (HPLC-MS/MS) and established cut-off values.

Methods

We used the hydrazine derivatization method to measure succinylacetone in 127 DBSs showing normal results in the newborn screening test and 93 DBSs showing increased tyrosine levels. We established cut-off values using the 99.9th percentile value or median+5 standard deviation value.

Results

Succinylacetone levels determined by our method were well-correlated with the results recommended by the Centers for Disease Control and Prevention for proficiency testing (r=0.9968). The succinylacetone levels in normal newborn DBSs were significantly lower than those in DBSs with high tyrosine levels (P < 0.001). The cut-off values were calculated to be 1.3 µM from the results of 127 normal DBS samples and 2.2 µM from 220 DBSs, including in 93 newborns with TNT.

Conclusions

Measurement of succinylacetone in DBSs by HPLC-MS/MS is useful in individuals with increased tyrosine concentrations and can be used for rapid differential diagnosis of tyrosinemia when an appropriate cut-off value is established.

Copyright © 2019. Korean Association of Medical Journal Editors.