What is Carnitine Uptake Disorder ?

Carnitine (CAR-NA-TEEN) uptake disorder or CUD is a fatty acid oxidation disorder. When the body needs energy, it begins by using sugar in the form of glucose. Once it runs out of glucose, it then turns to fats as an energy source. Our bodies rely on fat when we don’t eat for a stretch of time – like when we miss a meal or when we sleep. We get most of our carnitine from the food we eat. Carnitine helps the body make energy from the fat in food. It also helps us use fat already stored in the body. In CUD, the body has trouble using fats to make energy because of low carnitine levels.
Are there other names for CUD?
Yes, it can also be called primary carnitine deficiency and carnitine transporter defect.
What are the signs and symptoms?
People with CUD can have many different symptoms. Some people have no symptoms at all while others have severe symptoms from the time they are born. Severe symptoms may include:

• A weak, large heart
• Confusion
• Vomiting
• Muscle weakness
• Low blood sugar

No matter what usual symptoms people have, everyone who has the gene that causes CUD may be at increased risk for:

• Heart problems
• Liver problems
• Low blood sugar

Even people with no symptoms may be at risk for problems if their body is stressed such as during surgery or not eating for long periods (fasting).
How is carnitine uptake disorder treated?
CUD symptoms can be triggered by not eating for long periods of time. People with CUD should eat small, frequent meals and snacks and avoid fasting. Special diets (e.g. vegetarian, vegan) may not provide the body with enough carnitine. Before starting any special diets, people with CUD need to talk to a registered dietitian.

a. People with CUD should take carnitine supplements
Carnitine is prescribed to people with carnitine uptake disorder (CUD). Taking daily carnitine increases the low levels of carnitine in the body so that fats can be made into energy. Carnitine is available in liquid or pill form.

b. People with CUD should avoid antibiotics containing pivalic acid (PEE-VALL-IC AS-ID) (i.e. pivampicillin, pivmecillinam, cefditoren pivoxil, cefcapene pivoxil, cefetamet pivoxil, cefteram pivoxil, pivaloxylmethylcephem, pivcephalexin, tebipenem pivoxil)

If your doctor is prescribing an antibiotic, be sure to check with your pharmacist to see if the antibiotic contains pivalic acid which can lower carnitine levels and trigger CUD symptoms.

c. People with CUD should avoid valproate (VAL-PRO-ATE) (i.e. Epival (EPPEE-VAL), Depakene (DEPP-A-KEEN)
Valproate is an anti seizure medication that is used to treat epilepsy, migraines, anorexia nervosa, anxiety disorder, panic disorder, post traumatic stress disorder and bipolar disorder. Valproate can lower carnitine levels and trigger CUD symptoms.

People with CUD need to be aware that symptoms can get worse when they are ill, and especially when they are ill and not eating. It is important to try to continue to eat or drink fluids while ill and to continue taking the carnitine supplements. If you are ill with a cold or flu, drink lots of fluids and eat as you are able. If you are vomiting or have diarrhea, drink 30 mL of a clear liquid every 20 minutes for one hour. Examples are apple or grape juice mixed to half strength with water, rehydration drinks (e.g. Gatorade), weak tea with sugar, clear broth and Jell-O. Avoid citrus juices like orange juice. When your stomach has settled, you can begin eating clear soups, mild foods and liquids. Good choices are Jell-O, dry toast, crackers and cooked cereal.

Your doctor will arrange:
  • blood tests to monitor the carnitine levels in the blood, CK levels and liver function
  • echocardiograms (heart ultrasounds) to look for changes in the heart muscle
  • ECGs to look for changes in heart electrical conduction
How do people get carnitine uptake disorder?
Carnitine uptake disorder is an inborn error of metabolism. It is genetic. This means that the person has the disorder from the time they are conceived. At conception, the baby receives two sets of genetic material, one from the mother, and one from the father. This genetic material, called DNA, comes in units called genes. Each pair of genes gives instructions for specific activities that help our bodies grow and function. For example, our genes determine our eye and hair colour, if we are male or female, and how tall we are.

Sometimes genes can have changes (mutations—MEW-TAY-SHUNS) that cause them not to work properly.

In carnitine uptake disorder, there is a mutation in the genes that give information on how the body breaks down fats to make energy. CUD is an autosomal recessive condition meaning that the disorder is caused by inheriting two copies (one from each parent) of the gene with the mutation. If a person only has one copy of the gene with the mutation in it, they are a carrier for carnitine uptake disorder but are not affected. If both parents are carriers, there is a 1 in 4, or 25% chance with each pregnancy of the child being affected with carnitine uptake disorder. Boys and girls are equally affected.

People with the disorder will always pass on one of the CUD mutations to his/her children.
Management of CUD in pregnancy
Carnitine levels are lower during pregnancy. Ask your family doctor to refer you to a metabolic or genetic specialist before you get pregnant (or as soon as you know you are pregnant) to discuss increasing your carnitine supplements and monitoring of carnitine levels during pregnancy.
Related Organizations
The Adult Metabolic Diseases Clinic
Vancouver General Hospital
Diamond Health Care Centre
4th Floor, 2775 Laurel Street
Vancouver, BC V5Z 1M9
(604) 875-5965