Elevated
levels of the liver enzymes alanine and aspartate aminotransferase (ALT and AST)
are associated with a greater 10-year risk of death in the general population,
regardless of presence of viral hepatitis or other known liver disease, according
to a study presented last month at the American Association for the Study of Liver
Diseases (AASLD) annual meeting in Boston.
Researchers
from the Mayo Clinic in Rochester, MN, analyzed data from all community residents
who had their ALT or AST measured during 1995. Subjects were followed forward
and their survival was determined. In order to exclude patients with abnormal
liver function tests due to pre-existing terminal illness, deaths within the first
2 years were excluded.
Results
A total of 6792 subjects had ALT measured at least once, of whom 5885 had levels
less than the upper limit of normal (ULN) and 907 had abnormal results.
AST was measured at least once in 18,330 individuals, of whom 15,991 had normal
levels and 2339 had abnormal levels.
Over 10 years, there was a nearly linear relationship between aminotransferase
levels and standardized mortality risk.
Subjects with normal AST or ALT had lower-than-expected mortality rates.
The risk of death among subjects with normal ALT was 0.61, compared with 1.22
for those with elevated levels (P < 0.22) and 1.63 for those with levels >
2 x ULN (P < 0.01).
For subjects with normal AST, the mortality rate was 0.95, compared with 1.33
for those with elevated AST (P < 0.01) and 1.79 for those with levels >
2 x ULN (P < 0.01).
Conclusion
"Serum
levels of AST and ALT are predictive of future mortality in community populations,"
the researchers concluded. "These data suggest that screening for abnormal
AST or ALT should be considered as an important component of general medical examination." "Know
Your ALT" Campaign
At
the conference, AASLD launched a public education campaign recommending that Americans
pay more attention to ALT as an important marker of liver health and disease --
especially as levels of obesity rise and more people develop fatty liver disease.
The
association also urged the recalibration of what is considered normal ALT to reflect
levels in individuals with healthy livers. Existing so-called "normal"
references ranges may be based on populations that include apparently healthy
individuals with unrecognized liver disease related to the metabolic syndrome,
fatty liver, use of alcohol or toxic drugs, or undiagnosed viral hepatitis.
According
to AASLD, persistently elevated ALT should always be further evaluated for a cause,
given that too many practitioners currently ignore minor elevations in asymptomatic
individuals. Diagnosis of liver disease at early, more treatable stages is crucial,
not least due to the dire shortage of donated livers for transplantation.
Further,
the organization stated, "ALT is not only an indicator of liver disease but
also a gauge of general health, as there is a strong relationship between ALT
activity and mortality, even when the life-threatening process does not originate
from the liver."
AASLD
intends to promote ALT as a routine indicator of overall health, similar to cholesterol
or blood pressure.
11/14/06
Reference W
Kim, J T Benson, T M Therneau, and others. Serum Aminotransferase Concentrations
and Risk of Mortality in a Community Population. 57th AASLD. Boston, MA. October
27-31, 2006. Abstract 1251.
A total of 6792 subjects had ALT measured at least once, of whom 5885 had levels
less than the upper limit of normal (ULN) and 907 had abnormal results.
