A
new cohort study of male adolescent offenders in Australia has identified an upper
limit for the liver enzyme alanine aminotransferase (ALT) that is more sensitive
for the diagnosis of liver disease. The findings could facilitate targeted interventions
for the youths in this group, who are at high risk for HCV
infection and obesity-related liver disease.
The
study was reported in the December issue of Hepatology, a journal published
by John Wiley & Sons on behalf of the American Association for the Study of
Liver Diseases (AASLD). The
article is available online at Wiley Interscience.
Few
studies have examined the liver health of at-risk adolescents, or reported associations
between liver biochemistry and hepatitis C virus
(HCV) or metabolic liver disease.
Researchers
David van der Poorten, MD, Dianna Kenny, and Jacob George of Sydney University
analyzed data from a large cohort of young male offenders under supervision by
the New South Wales Department of Juvenile Justice in Australia, who took part
in a comprehensive health study funded by the Australian Research Council, NSW
Department of Juvenile Justice, and Justice Health.
The
researchers sought to create a new definition for the normal upper limit of liver
biochemistry, to define the associations and implications of raised ALT, and to
understand the risk factors and associations with hepatitis C.
They
examined the results of liver function tests and lipid measurements using blood
samples from 439 young male offenders who agreed to participate in the health
survey between October 2003 and December 2005. They also considered clinical,
demographic, and lifestyle data and performed statistical analyses to determine
relevant associations.
They
determined the upper limit of normal for liver enzymes using the liver function
tests of the participants at lowest risk of liver disease. These young men had
normal body mass index (BMI), cholesterol, triglycerides, and blood pressure,
did not have hepatitis B or C, and did not report heavy alcohol consumption.
The
researchers determined that the upper limits of normal were:
These
values are significantly lower than current upper limits for these tests, which
usually range from 45-55 IU/L.
Applying
these cutoffs to all participants, they found that 17% had elevated ALT. Compared
to those with normal ALT, "there was a strong association for overweight
or obesity," the authors reported. "To prevent further hepatic damage
and to minimize cardiovascular and diabetes risk, targeted interventions in adolescents
at the earliest stages of metabolic dysfunction are a particularly high priority."
The new upper
limits also detected 80% of the HCV-infected participants, who were significantly
more likely to have injected drugs in the past 12 months. A 1-year follow-up blood
test of 81 of the original participants showed additional incidence of HCV antibodies,
suggesting a new infection rate of at least 3.7% per year.
The
results indicate a worrying level of HCV exposure among this population. "Hence,
greater education regarding blood borne viruses, risk factors for transmission
and implementing harm minimization strategies in this population is crucial,"
the authors recommended. They also suggested routine hepatitis B vaccination.
In conclusion,"
the invetsigators wrote, "This study has provided a wealth of clinical and
health related data relevant to adolescents. The new definition of normal adolescent
ALT allows greater sensitivity in diagnosing early liver disease."
In
addition, they stated, "By identifying those with hepatitis B-, hepatitis
C- and obesity-related liver disease, targeted interventions can and should be
implemented to minimize future health-related morbidity."
02/26/08
Reference
D van der Poorten, D Kenny, T Butler, and others. Liver Disease in Adolescents:
A Cohort Study of High-Risk Individuals. Hepatology 46(6): 1750-1758. December
2007.
