Evaluation of factors influencing accuracy in the analysis of succinylacetone in dried blood spots. 
Dried blood spots offer specific advantages over conventional blood collection methods, but with certain limitations.  This article aims to evaluate factors which affect succinylacetone test in dried blood spots.  Whole blood with defined hematocrit and blood volume spiked with succinylacetone was spotted on filter paper, and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS).  Four hematocrit levels (30%, 40%, 50%, and 60%) and five blood volume levels (10, 30, 50, 70, and 100 μl) were tested.  Succinylacetone concentration increased with increasing hematocrit, large bias from added concentration was found to be - 45% when hematocrit was 30%, as the difference of hematocrit level between the calibrator and QC sample increased, the bias from nominal value was increased.  Blood volume also has effect on succinylacetone concentration level, but the accuracy was <15% when blood volume was 10 to 50 μl, and >20% as the blood volume went to ≥70 μl.  Both hematocrit and blood volume have effect on analysis of succinylacetone in dried blood spots, the effect of hematocrit is more significant, due to hematocrit level of majority Type I tyrosinemia patients is low, diagnoses may be missed by using dried blood spots to analysis.