Development of tandem mass spectrometry-based creatinine measurement using dried blood spot for newborn mass screening.

BackgroundCongenital anomalies of the kidney and urinary tract (CAKUT) are the most prevalent etiologies of pediatric chronic kidney disease (CKD). However, no robust mass screening methods have been developed to detect patients with CAKUT, making early intervention to prevent progressive renal failure challenging.MethodsWe applied tandem mass spectrometry (MS/MS) to measure the creatinine (Cr) value from dried blood spot (DBS) analysis, which has been used for newborn mass screening. Subsequently, we evaluated the correlation between DBS Cr measured by MS/MS and serum Cr measured by the conventional method in pediatric patients with CKD. Finally, DBS Cr was measured in 190 full-term, healthy newborns on days 4-6 after birth.ResultsWe established a system of MS/MS-based measurement of Cr from DBS. Measured DBS Cr in the pediatric patients showed a strong association with serum Cr (r=0.86; P<0.01). The median DBS Cr value in newborns was 0.222 (interquartile range: 0.189, 0.269) mg/dl. No significant correlations were found between DBS Cr values and body weight, Apgar score, gestational age, and sex in newborns.ConclusionWe successfully established a method for MS/MS-based measurement of Cr for newborn screening and determined normal reference values for full-term newborns.