What specimen type is primarily used for newborn screening?

The primary specimen type used for newborn screening is dried blood spot. This method involves collecting a small amount of blood from a newborn, typically obtained via a heel prick. The blood is then spotted onto filter paper, allowed to dry, and sent to a laboratory for analysis.

Dried blood spots are advantageous in newborn screening due to their ease of collection, transportation, and storage. They can be easily mailed and do not require refrigeration for short durations, making them very practical in the early days of a newborn's life when immediate access to venous collection can be challenging.

While capillary blood can also be collected during the newborn screening process, it is primarily the dried blood spot method that is standardized and widely adopted because it allows for the assessment of a wide range of metabolic and genetic disorders with a small volume of blood. Venous blood is usually drawn for more specific tests rather than routine newborn screenings, and urine specimens are not typically used in the initial newborn screening process. Hence, dried blood spots remain the cornerstone of newborn screening methodologies.