Answers to your frequently asked questions
FAQs
The urea cycle disorder (UCD) medicines that are currently approved in the United States are sodium phenylbutyrate and glycerol phenylbutyrate. These are used in combination with a protein-restricted diet and, in some cases, essential amino acid supplements.
Sodium benzoate in a medication combined with sodium phenylbutyrate is also sometimes given through a central vein catheter by a healthcare professional. Hemodialysis can also lower ammonia levels during acute hyperammonemia. Liver transplant is the only “cure” for UCDs.
Yes. Unfortunately, brain damage can occur even if ammonia levels are slightly increased over time. It’s important to speak with a healthcare team to make sure ammonia levels are monitored appropriately.
Key Terms
Amino acids
Molecules that make up proteins.
Ammonia
Ammonia is made as a waste product when the body digests protein.
Ammonia-clearing medicines
Also known as ammonia-scavenging drugs (or nitrogen-scavenging drugs), these drugs help clear ammonia from the body and prevent the buildup of ammonia.
Amino acid supplements
Amino acid supplements are nutritional supplements, such as L-citrulline or L-arginine. The doctor may have you or your loved one take nutritional supplements with amino acids as part of the treatment plan.
Biochemical geneticists
Biochemical geneticists are genetic specialists who study DNA and cell development.
Dietitians/nutritionists
Dietitians are experts in identifying the right foods and diet based on medical conditions or body type.
Essential amino acids
Essential amino acids cannot be made by the body. As a result, they must come from diet.
Genetic counselors
Genetic counselors are genetic specialists who focus on how genes are passed down.
Glycerol phenylbutyrate
A UCD treatment that is a liquid and is measured and taken with or after meals. You should speak with the doctor to determine if this treatment is right for you or your loved one.
Hemodialysis
A procedure that helps the body filter toxins and extra fluid from your blood when your kidneys are not performing as well as they should be.
Hyperammonemia
Any increase in ammonia in the blood that is higher than normal.
Hyperammonemic crises
Hyperammonemic crises (HACs) happen when blood ammonia levels are too high. An HAC is a serious emergency that can result in brain damage or even death.
Inherited disorder
An inherited disorder means it is passed down through your genes, and you are born with it.
Intensivists
Intensivists are people who take care of someone who is critically ill.
Laboratory technicians
Laboratory technicians work in a laboratory performing procedures and running tests.
Liver transplant
The only known “cure” for UCD is a liver transplant, which is a surgery that removes and replaces the liver with another one. This surgery carries significant life-threatening risk and may not completely fix all issues associated with UCD.
Nephrologists
Nephrologists are doctors who work to keep the kidneys healthy.
Nitrogen scavengers
UCD treatments that help clear ammonia from the body and prevent the buildup of ammonia.
Neuropsychologists
Neuropsychologists specialize in the relationship between brain and behavior.
Nurses
Nurses work with doctors and healthcare professionals and are trained to give medical care to people who need it.
Pharmacists
Pharmacists specialize in the right way to use, store, preserve, and provide medicine.
Protein-restricted diet
A protein-restricted diet is 1 of 3 key components in the treatment of UCDs; it limits the amount of protein eaten and balances it with growth requirements.
Sodium benzoate
A UCD treatment that is approved in the US only in a medication with sodium phenylacetate for injection through a catheter placed in a central vein.
Sodium phenylbutyrate
A UCD treatment that is prescribed as tablets or as powder that you can mix with foods or liquids. Both are taken with meals. You should speak with the doctor to determine if this treatment is right
for you or your loved one.
Transplant surgeons
Transplant surgeons are a type of surgeon who specialize in transplanting one person’s organs into another person’s body.
Urea
Urea is the waste produced by the body that kidneys help filter out through urine.
Urea cycle
The urea cycle is the process that turns harmful ammonia, which is created when the body digests protein, into urea so that the body can get rid of it through urine.
Urea cycle disorders
Urea cycle disorders (UCDs) are a group of rare inherited disorders. In people with UCDs, the process that turns toxic ammonia into urea so that the body can get rid of it through urine is not working correctly.
Sources
- Häberle J, Burlina A, Chakrapani A, et al. Suggested guidelines for the diagnosis and management of urea cycle disorders: first revision. J Inherit Metab Dis. 2019;42(6):1192-1230.
- Shchelochkov OA, Dickinson K, Scharschmidt BF, Lee B, Marino M, Le Mons C. Barriers to drug adherence in the treatment of urea cycle disorders: assessment of patient, caregiver and provider perspectives. Mol Genet Metab Rep. 2016;8:43-47.
- Enns GM, Porter MH, Francis-Sedlak M, Burdett A, Vockley J. Perspectives on urea cycle disorder management: results of a clinician survey. Mol Genet Metab. 2019;128(1-2):102-108.
- Gropman AL, Prust M, Breeden A, Fricke S, VanMeter J. Urea cycle defects and hyperammonemia: effects on functional imaging. Metab Brain Dis. 2013;28(2):269-275.
- Batshaw ML, Tuchman M, Summar M, Seminara J, Members of the Urea Cycle Disorders Consortium. A longitudinal study of urea cycle disorders. Mol Genet Metab. 2014;113(1-2):127-130.
- Weiner ID, Mitch WE, Sands JM. Urea and ammonia metabolism and the control of renal nitrogen excretion. Clin J Am Soc Nephrol. 2015;10(8):1444-1458.
- Häberle J, Boddaert N, Burlina A, et al. Suggested guidelines for the diagnosis and management of urea cycle disorders. Orphanet J Rare Dis. 2012;7:32.
- Ah Mew N, Simpson KL, Gropman AL, Lanpher BC, Chapman KA, Summar ML. Urea cycle disorders overview [updated June 22, 2017]. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews® [Internet]. University of Washington; 1993-2022. Accessed March 20, 2022. https://www.ncbi.nlm.nih.gov/books/NBK1217/
- RAVICTI® (glycerol phenylbutyrate) oral liquid. Prescribing information. Deerfield, IL: Horizon Therapeutics.
- BUPHENYL® (sodium phenylbutyrate). Prescribing information. Lake Forest, IL: Horizon Therapeutics.
- AMMONUL® (sodium phenylacetate and sodium benzoate). Prescribing information. Scottsdale, AZ: Ucyclyd Pharma, Inc.
- Gupta S, Fenves AZ, Hootkins R. The role of RRT in hyperammonemic patients. Clin J Am Soc Nephrol. 2016;11(10):1872-1878.