Abnormal SCID Newborn Screen Resources


Have you been contacted because your infant’s newborn screening test indicated they may have SCID?

What does it mean?

An abnormal result for SCID on a Newborn Screen Report means that your baby has low T cell receptor excision circles or TRECs. An abnormal result, also called positive, out-of-range, or high-risk, is a concern because it means your baby may have low T cells.

T cells are one part of the body’s white blood cell system and are an important part of the immune system that prevents life-threatening infections. Your baby may look healthy, but it is very important to follow up with your doctor to learn more.

The purpose of the SCID test is to identify babies who may have SCID, but an abnormal screen does not mean your baby has SCID. Other conditions which may result in an abnormal result for SCID include:

  • Prematurity
  • DiGeorge Syndrome
  • Combined Immune Deficiency
  • Secondary T cell deficiency
  • Lymphopenia
  • Congenital Athymia
  • Other congenital abnormalities associated with low T cells
  • Transient immunosuppression

You will be asked to bring your baby in for more testing. If your baby was born prematurely, doctors might repeat the screening test when you baby reaches their corrected gestational age. Waiting to collect the second specimen allows the infant’s immune system time to mature, with the possibility of normalized TREC values. Infants with “urgent” positive values (zero or very few TRECs) are at very high risk for SCID, and consequently, their follow-up is expedited. Those infants are typically referred immediately for flow cytometry and evaluation by a specialist in pediatric immunology. Apparently healthy infants with a positive, but not urgent TREC result are also referred. Flow cytometry measures the individual cells in a sample of blood. This is a diagnostic test used to determine if your baby has T cells.

Why is the Newborn Screening test for SCID called a TREC test?

The Newborn Screening test measures the number of T cell receptor excision circles (TRECs) found in a spot of blood taken from the baby’s heel. The number of TRECs indicates how many T cells the baby has. 

Abnormal, Positive, Negative what does it all mean?

A Negative result indicates normal TREC levels. A baby with a negative result for SCID is not considered to be at risk of having SCID.

A Positive test indicates Abnormal or low TREC levels. In this case, further testing is needed to see if the baby has a condition affecting their T cells.

Is it common to have an abnormal result for SCID?

Most infants who receive an abnormal result for SCID newborn screening do not have SCID. Low birthweight, preterm and ill infants cared for in a neonatal intensive care unit (NICU) have higher rates of false positives. SCID is diagnosed in approximately 1 in 58,000 births.

What do I do?

It is important to follow up with your physician or the immunologist if you’ve been referred to one. You should follow your provider’s instructions for what steps to take.

While you wait for testing results it’s important to protect your infant from any risk of infection. Make it a habit to always wash your hands well before picking up your baby.

Your doctor may recommend that you only use commercial infant formula. This is to reduce the risk of transferring CMV and other viruses to your baby.

If you’ve been released from the hospital, you should isolate your baby at home. While friends and family will want to meet your new baby, you should hold off on having everyone meet your new little one. If you have older children who attend school or outside activities you may want to keep them separate from the baby. Likewise, pets should also be kept separate.

Your doctor will want to hold off on any vaccines, especially live vaccines such as rotavirus (oral) vaccine, and may want to start your baby on prophylactic medication to help prevent infection.

To learn more about what it means to have Low T Cell Results. Click the link below to download the Pamphlet on Low T Cell Results.

If you’re ready to learn more about SCID Types and Treatments follow the link to “SCID Types and Treatments”.