Renal insufficiency mimicking glutaric acidemia type 1 on newborn screening

BackgroundGlutaryl carnitine (C5DC) in dried blood spots is used as a biomarker for glutaric aciduria type 1 (GA-1) screening. C5DC, however, is the only screening marker for this condition, and various pathological conditions may interfere with C5DC metabolism. Recently, C5DC elevation has been reported in cases of renal insufficiency. MethodFive patients who were positive for GA-1 on newborn screening with tandem mass spectrometry between September 2012 and March 2015 at Kobe University Hospital were enrolled in this study. ResultsGA-1 was not confirmed on urinary organic acids analysis in any of the patients. C5DC decreased immediately in four patients, but one patient, who had high C5DC for at least 4 months, was diagnosed with bilateral renal hypoplasia. ConclusionIn the case of persistently elevated C5DC, renal insufficiency should be considered as a differential diagnosis.