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Urea Cycle Disorder
May 1, 2007
Digesting protein may be a hidden
problem for some, according to the Harvard
Health Letter
BOSTON — Protein metabolism
presents some serious waste management challenges
for the body. When protein is broken down, one of
the by-products is ammonia. Ammonia is toxic, so
our bodies have elaborate systems for getting rid
of it. Most of the detoxifying work falls to our
liver. There, ammonia travels a multistep pathway
featuring five enzymes that turn it into urea, to
be excreted in urine. People with rare genetic deficits
that interfere with the urea cycle often die in childhood.
Other mutations, though, may be responsible for some
problems in adults, reports the May 2007 issue of
the Harvard Health Letter.
One in 8,000 American children has a genetic defect
that causes one or more of the enzymes involved in
ammonia processing to be defective or scarce. As these
children start to consume protein, the ammonia begins
to pile up. Treatment includes protein restriction,
medications that sop up extra ammonia, dialysis, and
possibly liver transplant. The death rate is high.
Urea cycle disorders are viewed as rare and primarily
pediatric conditions, but there might be a whole range
of unrecognized, genetically determined problems with
protein metabolism experienced by adults. Some people
may have mild mutations that compromise a gene’s
function and cause slight symptoms. This may explain
why one person eschews meat while another loves nothing
more than a steak meal. Defects in protein metabolism
may also explain why some people have bad reactions
to high-protein diets like the Atkins diet.
The Harvard Health Letter notes that someday
genetic tests might be used routinely to diagnose such
metabolic disorders, but for now much more research
is needed.
Also in this issue:
- Open-fit hearing
aids
- Is fructose unhealthy?
- Standard versus digital mammograms
- Atkins wins with weight
loss
- By the way doctor: Can exercise and diet cure diabetes?
Does asthma go
away?
 Related
Information
Harvard Health Letter is available
from Harvard Health Publications, the publishing division
of the Harvard Medical School. You can subscribe at www.health.harvard.edu/health or
by calling 1-877-649-9457 toll-free.
About Harvard Health Publications
Harvard Health
Publications publishes five monthly newsletters—Harvard
Health Letter, Harvard
Women's Health Watch, Harvard
Men's Health Watch, Harvard
Mental Health Letter, and Harvard
Heart Letter—as well as more than 50 special health
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faculty physicians at Harvard Medical School and its
world-famous affiliated hospitals. For more information
about Harvard Medical School publications, please visit
our Web site, www.health.harvard.edu.
Source: Harvard
Health Publications
Contact: hhpmedia@hms.harvard.edu
Web site: http://www.health.harvard.edu |
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