Newborn metabolic screening for metabolic diseases is commonly performed using which specimen?

• A. Cord blood
• B. Heel-stick blood sample
• C. Urine sample
• D. Saliva swab

Answer: (B)

Newborn metabolic screening uses a dried blood spot collected from a heel prick. A tiny amount of blood is dropped onto filter paper and allowed to dry, then sent to the laboratory for testing that can detect many metabolic and endocrine disorders. This method is ideal because it requires only a small blood volume, the dried spot is stable at room temperature, and the sample is easy to collect, transport, and store for high-throughput screening. Timing matters too; collecting after the newborn has had a feeding and is at least about 24 hours old increases the test’s sensitivity and helps reduce false negatives. Cord blood, urine, or saliva aren’t standard for routine metabolic screening because they don’t provide the same reliability or practicality for the broad panel of disorders tested.