MCAD deficiency is diagnosed through newborn screening followed by genetic testing.

  • Newborn screening. In the U.S., all states screen for MCAD deficiency at birth. If screening levels are abnormal, additional testing can be done.
  • Genetic testing. Genetic testing can reveal the abnormal gene that causes MCAD deficiency. Depending on the type of test, a sample of blood, skin or other tissue is collected and sent to a lab for analysis. Your doctor may also recommend testing family members for this gene. Talk with your doctor, a medical geneticist or a genetic counselor about the testing process and what the results mean.

Episodes of low blood sugar (hypoglycemia) thought to be caused by MCAD deficiency are evaluated by a discussion of signs and symptoms, as well as dietary habits, usually followed by lab tests to identify problems with metabolism and treat or prevent complications.


Newborn screening at birth allows MCAD deficiency to be diagnosed and treated early, before symptoms occur, preventing complications. Once identified, the disorder can be managed through diet and lifestyle.

The main goal of treatment for MCAD deficiency is to prevent problems caused by hypoglycemia from occurring. Infants with MCAD deficiency require frequent feedings with adequate calories from complex carbohydrates to maintain blood sugar and avoid hypoglycemia. Children and adults also require adequate complex carbohydrates on a regular schedule of eating. Work with your health care team, including a dietitian, to develop a treatment plan tailored to your childꞌs or your metabolic needs.

The length of time that is safe for fasting may vary with age and your health care teamꞌs recommendations. For example, during the first four months of life, well infants' fasting time may be no longer than four hours. Fasting time may be gradually increased up to 12 hours by one year of age. Children and adults should not fast for longer than 12 hours.

Recommendations to prevent hypoglycemia generally include:

  • Avoid fasting longer than recommended by your health care team
  • Eat regular meals and snacks with adequate calories from complex carbohydrates, such as brown bread, rice, pasta and cereal, for energy needs
  • Choose foods that are high in complex carbohydrates and lower in fat
  • Increase calories by eating extra complex carbohydrates during illness, stress or increased activity

Your health care team may recommend a carnitine supplement to aid in fatty acid metabolism.

Talk with your doctor about what to do if hypoglycemia signs and symptoms develop so that you have an emergency plan. Strategies may include:

  • Taking simple carbohydrates, such as sugar (glucose) tablets or sweetened, nondiet beverages.
  • Seeking emergency medical care if unable to eat or for diarrhea or vomiting. An intravenous (IV) line for extra glucose and additional treatment may be needed.

Lifestyle and home remedies

Parent and family understanding of the condition is critical to ongoing care and prevention of hypoglycemia episodes and complications. Prevention tips include:

  • Avoid fasting
  • Know the warning signs of hypoglycemia and treat it immediately
  • Eat complex carbohydrates before extra activity or exercise
  • Increase calories with extra complex carbohydrates during illness, stress or increased activity
  • Always carry complex carbohydrate snacks
  • Always carry a source of simple carbohydrates to treat hypoglycemia

If you or your child has been diagnosed with MCAD deficiency, wear a medical alert bracelet or necklace or carry a medical card. This lets health care providers know of your condition, even in an emergency. Ask your doctor about information for health care professionals that you can carry with you in case your child needs emergency care.

Coping and support

Caring for a child or family member with a lifelong disorder such as MCAD deficiency can be stressful and exhausting. Consider these strategies:

  • Learn about the disorder. Learn as much as you can about MCAD deficiency. Then you can make the best choices and be an advocate for yourself or your child. Help family members, caregivers, teachers and friends understand the condition, the care needed, and the consequences of not following dietary instructions.
  • Find a team of trusted professionals. You'll need to make important decisions every day about care. Medical centers with specialty teams can offer you information about the disorder, as well as nutritional advice and support, and can help you manage care.
  • Seek out other families. Talking to people who are dealing with similar challenges can provide you with information and emotional support. Ask your doctor about support groups in your community. If a group isn't for you, maybe your doctor can put you in touch with a family who has dealt with the disorder. Or you may be able to find a group or individual support online.
  • Ask for help from family and friends. Ask for or accept help from family and friends in caring for your loved one when needed. Take time for your own interests and activities. Counseling with a mental health professional may help with adjustment and coping.
May 30, 2020
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