Positive Newborn Screen for MCAD -- Now What?

Stephanie L. Austin, MS, MA; Laura A. Stokowski, RN, MS


July 10, 2014

Editorial Collaboration

Medscape &

Follow-up Exam and Testing

The parents bring their infant in to see you early the following morning. You take a history from the parents, focusing on the infant's health and behavior and whether the parents have noticed anything unusual. You assess the infant's pattern and duration of sleeping, appetite, feeding behavior, and the occurrence of diarrhea or vomiting. The mother reports that her milk came in fully on day 4, and the baby is breastfeeding about every 2 hours during the daytime but has slept as long as 5 hours at night without waking to feed. He does not spit up. His diapers are now wet with every change, and his stools are yellow.

Your physical examination of the infant shows slight jaundice but no other abnormalities. His heart rate is 128 beats/min, respiratory rate is 36 breaths/min, and tympanic membrane temperature is 98.4 °F. His breath sounds are clear, and there is no murmur. A mid-sternum transcutaneous bilirubin level is 6.4 mg/dL. His weight is 3800 g (increased 25 g from birth weight of 3775 g). His skin turgor is normal, and his muscle tone and reflexes are appropriate. He is alert and happy during the examination. His circumcision is healing with no evidence of infection. The parents seem anxious, however, and are asking many questions about the newborn screening test and about doing genetic tests.

These physical exam findings reflect that the infant is healthy and is not showing any signs of a metabolic disorder, infection, or illness. You have blood drawn from the infant in your office for a follow-up plasma acylcarnitine profile and plasma carnitine levels as recommended by the state laboratory and the American College of Medical Genetics.[12,13] You also collect urine for urinary organic acids. You expect to receive the results within a few days.


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