What is the significance of elevated propionylcarnitine (C3) in newborn screening tests?

Elevated propionylcarnitine (C3) levels in newborn screening tests are particularly significant as they serve as a marker for Propionic Acidemia. This condition is a metabolic disorder resulting from the deficiency of the enzyme propionyl-CoA carboxylase, which is essential for the metabolism of certain amino acids and fats. When this enzyme is deficient, there is an accumulation of propionic acid and related metabolites, including propionylcarnitine, leading to the observed elevation in newborn screening tests.

Identifying elevated C3 in newborn screening allows for early diagnosis and management of Propionic Acidemia, which can significantly reduce the risk of severe complications associated with the disorder, such as metabolic crises, developmental delays, and other serious health issues. Newborn screening programs specifically assess C3 levels as a proactive measure to detect this potentially life-threatening condition early on.

While elevated C3 may also be associated with other conditions, its specific link to Propionic Acidemia makes it a critical marker in metabolic screening.