Unexplained elevations in alanine aminotransferase in individuals with the metabolic syndrome: results from the third National Health and Nutrition Survey (NHANES III).
BACKGROUND
Unexplained elevations in alanine aminotransferase (ALT) level have been suggested to signify the presence of nonalcoholic fatty liver disease (NAFLD) in adult NHANES III participants. In this study, we examined the relationship between unexplained elevations in ALT level and the metabolic syndrome and the relationship between unexplained elevations in ALT level and microalbuminuria.


METHODS
We examined the prevalence and predictors of unexplained elevations in ALT level in 4376 adult NHANES III participants with the metabolic syndrome. Metabolic syndrome was defined according to Adult Treatment Panel III criteria, and the presence of unexplained elevations in ALT level was defined based on the previously published criteria. Prevalence of microalbuminuria was compared between 710 individuals with unexplained elevations in ALT level and 1780 control subjects.


RESULTS
Prevalence of unexplained elevations in ALT level in individuals with the metabolic syndrome was 7% and was significantly higher than in those without the metabolic syndrome (3.5%; OR, 2.07; 95% CI, 1.78-2.41). Younger age, male gender, higher triglycerides or serum iron levels, low levels of certain antioxidants, and insulin resistance (or diabetes) were independently associated with unexplained elevations in ALT level in the metabolic syndrome. Prevalence of microalbuminuria was not different between individuals with unexplained elevations in ALT level and their control subjects (4.8% versus 6.2%, respectively; P = 0.2).


CONCLUSIONS
Individuals with the metabolic syndrome have a significantly higher prevalence of unexplained elevations in ALT level. Because unexplained elevations in ALT level may signify the presence of NAFLD, our data support the notion that NAFLD is part of the spectrum of the metabolic syndrome. However, no relationship was demonstrated between unexplained elevations in ALT level and microalbuminuria.
Liangpunsakul
Suthat
S
Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Chalasani
Naga
N
D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood*; D000419:Albuminuria / Q000201:enzymology / Q000453:epidemiology*; D000975:Antioxidants / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D005234:Fatty Liver / Q000201:enzymology / Q000453:epidemiology; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D007501:Iron / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000201:enzymology*; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D014280:Triglycerides / Q000097:blood
D000975:Antioxidants; D001786:Blood Glucose; D014280:Triglycerides; D007501:Iron; D000410:Alanine Transaminase