Used in research settings to quantitatively measure levels of Quinone Dihydrophthalidine Reductase (QDPR) in human biological samples such as serum, plasma, or tissue homogenates. This ELISA kit is particularly valuable in studies related to tetrahydrobiopterin (BH4) metabolism, as QDPR plays a critical role in regenerating BH4, a cofactor essential for neurotransmitter synthesis and nitric oxide production. It supports investigation into metabolic disorders like phenylketonuria (PKU) and other conditions linked to impaired aromatic amino acid metabolism. The assay enables high-throughput analysis with high sensitivity and specificity, making it suitable for clinical research, biomarker validation, and monitoring disease progression or therapeutic response in neurology and metabolic disease studies.