Rare Disease Day: Understanding Urea Cycle Disorders

Feb 26, 2015

In honor of Rare Disease Day, specialist pharmacists in the Accredo Rare Disease Therapeutic Center® provide tips for patients managing rare conditions such as urea cycle disorders.

  • Orphan Drugs
  • Adults
  • Caregivers
  • Children

On February 28, we will celebrate Rare Disease Day – an international advocacy day to bring recognition to rare diseases. In the U.S., conditions affecting fewer than 200,000 people are considered rare.

There are nearly 7,000 rare diseases affecting nearly 30 million Americans.

At Accredo, an Express Scripts company, pharmacists in the Rare Disease Therapeutic Resource Center® (TRC) have specialized training to assist with the complex care and treatment that these conditions require. Accredo provides specialized care for patients with rare diseases such as cystic fibrosis, enzyme deficiencies and urea cycle disorders.

Understanding the Condition

Urea cycle disorders (UCD) are a group of genetic diseases that affect the urea cycle. The urea cycle is the body’s way of neutralizing highly toxic ammonia, produced from protein breakdown, into the less toxic urea, which can be removed by the urine.

Individuals with UCD are deficient in proteins that carry out key parts of the urea cycle. If any part of the urea cycle isn’t functioning like it should, ammonia will build up. When ammonia levels get too high, this can cause damage to cells – particularly brain cells, leading to permanent neurological damage, seizures and coma.  Excess ammonia in the blood is also called “hyperammonemia.”

It is estimated that 1 in every 30,000 newborns suffers with a urea cycle disorder.

One form of UCD – deficiency of the N-Acetylglutamate Synthetase enzyme, or NAGS – is extremely rare, with no new U.S. diagnoses in more than 10 years. However, due to early and rapid neonatal mortality, NAGS and other urea cycle disorders are likely underdiagnosed, and the true number of individuals affected remains unknown. With disease onset in the first 30 days of life, NAGS deficient patients have a 50% mortality rate. It’s estimated that up to 20% of sudden infant death syndrome (SIDS) cases could be an undiagnosed urea cycle disorder. The severity and mortality rate of a urea cycle disorder is dependent on which enzyme is affected, how much it is still able to function, and the amount of stress on the urea cycle. Infection, injury, trauma and dietary protein intake can stress the body’s ability to manage blood ammonia levels if the urea cycle is defective.

However, recent advances in treatment and testing have reduced the mortality in children and adults.

Preventing Hyperammonemic Crises

There are several things patients with urea cycle disorders can do to minimize their chances of having a high blood ammonia crisis.

  • Practice good infection prevention, such as hand washing
  • Keep up to date on vaccines recommended by your treating physician, as vaccines do NOT trigger hyperammonemic episodes
  • Minimize contact with sick friends and family
  • Involve your physician treating your UCD in all aspects of your healthcare – including planning for non-UCD medications, treatments and procedures
  • Adhere to the special low-protein diet as recommended by your doctor
  • Take your medications as prescribed by your doctor
  • Recognize the signs of early hyperammonenemia such as irritability and vomiting
  • Be aware of what may trigger of metabolic crisis including fever and infection

Treatment  and Medication Tips

  • Ask your Accredo pharmacist about proper technique for administering UCD medications via a feeding tube
  • Wear a medical alert bracelet indicating you have a urea cycle disorder
  • Educate school staff, caregivers and family members on the signs of high-blood ammonia levels and emergency contact information
  • Keep all appointments for labs and check-ups with your physician
  • Use medication reminders to stay adherent 

Specialist pharmacists and nurses in the Rare Disease TRC are on call 24/7 to educate patients about medication administration and storage, discuss potential on drug or food interactions, and help manage medication side effects.

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