Newborn Screening for VLCAD Deficiency: What to Expect
Newborn screening (NBS) is a routine, life-saving test performed on all newborns in the United States. VLCAD deficiency is included on the Recommended Uniform Screening Panel (RUSP), which means hospitals and state labs automatically screen for it shortly after birth.
Newborn screening for VLCAD deficiency is done using a small amount of blood collected from your baby’s heel. This is often called a heel stick or blood spot screening. The blood drops are placed on a special card and sent to a state newborn screening laboratory for analysis.
During screening, a specialized machine measures levels of substances called acylcarnitines in your baby’s blood. These substances are produced when the body breaks down fat for energy. Babies with elevated levels of certain acylcarnitines may have VLCAD deficiency and require further evaluation.
This screening typically takes place within the first 24–48 hours after birth and is safe, quick, and standard across the United States.
How Newborn Screening Detects Possible VLCAD
State newborn screening programs use advanced technology called tandem mass spectrometry to analyze the dried blood spot. This allows laboratories to detect abnormal patterns of acylcarnitines that may indicate a fatty acid oxidation disorder, including VLCAD deficiency.
The key marker typically evaluated for VLCAD is an elevated long-chain acylcarnitine (especially C14:1). When these markers are outside the normal range, the screening result is flagged for follow-up.
What an “Out-of-Range” Newborn Screening Result Means
If your baby’s newborn screening result for VLCAD is out-of-range, your baby’s health care provider or the state newborn screening program will contact you directly. This result does not mean your baby definitely has VLCAD deficiency. Instead, it means:
Additional testing is needed
A medical professional has been alerted
Follow-up should occur as soon as possible
Early follow-up is extremely important because babies with VLCAD deficiency can develop serious symptoms if the condition is not identified and managed quickly.
What Happens After an Abnormal VLCAD Newborn Screening Result
If your baby’s screening result is out-of-range, confirmatory testing will be recommended. This may include:
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These tests measure how your baby’s body is processing fats and producing energy. Specialized labs analyze blood and urine for metabolic markers that can help confirm or rule out VLCAD deficiency and other metabolic conditions.
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Genetic testing looks for changes (variants) in the ACADVL gene, which is responsible for VLCAD deficiency. This test helps confirm a diagnosis and can also provide important information about the specific type and severity of the condition.
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This blood test provides a detailed measurement of acylcarnitine levels, the same markers evaluated during newborn screening but with more precision. An abnormal acylcarnitine pattern, particularly elevated long-chain markers, can help metabolic specialists determine whether VLCAD deficiency is likely.
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An echocardiogram is a painless ultrasound of the heart that allows doctors to evaluate heart structure and function. Because VLCAD deficiency can affect the heart in some cases, this test helps ensure early detection and monitoring of any potential cardiac involvement.
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In certain situations, a small skin sample may be collected to study how your child’s cells process fatty acids in a laboratory setting. This specialized test can provide additional confirmation if genetic or biochemical results are unclear and is typically ordered by a metabolic specialist.
These tests help determine whether your baby truly has VLCAD deficiency or if the screening result was a false positive.
Reassurance for Families Waiting on Results
Waiting for newborn screening follow-up can feel overwhelming and emotional. It is important to remember that early detection through newborn screening is designed to protect your baby’s health, and your medical team will guide you through each next step with care and urgency. Support and reliable information are available throughout this process if additional testing is needed.
Maddie’s Spark Foundation is here to support you every step of the way. We provide trusted resources, education, and guidance to help families understand VLCAD deficiency, navigate follow-up testing, and feel more confident as they begin this journey. You are not alone, and with the right information and medical care, families can move forward with clarity, support, and hope.
What Results May Indicate the Need for More Testing
A newborn screening report may recommend follow-up when:
Elevated long-chain acylcarnitines (especially C14:1) are detected
The acylcarnitine pattern suggests a possible fatty acid oxidation disorder
The result is labeled as “out-of-range,” “abnormal,” or “positive screen”
In many states, the newborn screening laboratory will also notify your baby’s pediatrician, a metabolic genetic specialist, and the state newborn screening follow-up team if a result is out-of-range. This rapid notification system is designed to ensure that babies receive timely evaluation, appropriate follow-up testing, and prompt medical care if needed.
Important: An Abnormal Screen Is Not a Diagnosis
It is essential for families to understand that newborn screening is a screening test, not a diagnostic test. False-positive results are uncommon but can occur. One known factor that may influence screening results is if a baby received carnitine supplementation before the screening was completed.
If VLCAD deficiency is confirmed, early diagnosis allows for immediate medical management, including nutrition planning and metabolic care. Prompt follow-up testing helps prevent serious complications such as low blood sugar, heart involvement, or metabolic crises. For this reason, families should complete all recommended follow-up testing as quickly as possible and stay in close communication with their pediatrician and metabolic specialist.