Ethnic differences in the link between insulin resistance and elevated ALT.
BACKGROUND
Nonalcoholic fatty liver disease (NAFLD) exhibits tight links with insulin resistance (IR) and the metabolic syndrome (MetS), a cluster of cardiovascular risk factors. Compared with non-Hispanic whites, non-Hispanic black adolescents have more IR but a lower prevalence of NAFLD and MetS. Our hypothesis was that IR would be a better predictor of alanine aminotransferase (ALT) elevations than is MetS among non-Hispanic blacks.


METHODS
We analyzed data from 4124 adolescents aged 12 to 19 years in the 1999 to 2010 NHANES, using unexplained elevations in ALT (>30 U/L) to characterize presumed NAFLD and using a pediatric adaptation of the Adult Treatment Panel III definition of MetS.


RESULTS
Prevalence of elevated ALT varied by race/ethnicity (Hispanics 13.7%, non-Hispanic white 8.6%, non-Hispanic blacks 5.4%, P < .0001). Among non-Hispanic whites and Hispanics, a classification of MetS performed well in identifying adolescents with elevated ALT (odds ratios [ORs] 9.53 and 5.56, respectively), as did MetS-related indices. However, among non-Hispanic blacks, the association between MetS and ALT elevations was smaller in magnitude and technically nonsignificant (OR = 3.24, P = .051). Furthermore, among non-Hispanic blacks, the presence of IR and elevated waist circumference performed more poorly at identifying ALT elevations (ORs 3.93 and 2.28, respectively: significantly smaller than ORs for non-Hispanic whites, P < .05), with triglyceride elevations being a better predictor (OR = 4.44).


CONCLUSIONS
Non-Hispanic black adolescents exhibit a lower relationship between IR and elevated ALT, supporting racial/ethnic differences in the link between MetS and NAFLD. These data may have implications regarding triggers for screening for NAFLD among non-Hispanic black adolescents, focusing particularly on those with triglyceride elevations.
Department of Pediatrics, University of Virginia, Charlottesville, VA, USA.
Mark D
MD
Deboer
R Constance
RC
Wiener
Barrett H
BH
Barnes
Matthew J
MJ
Gurka
D000293:Adolescent; D001741:Black or African American; D000410:Alanine Transaminase / Q000097:blood*; D002648:Child; D005234:Fatty Liver / Q000097:blood* / Q000208:ethnology*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D007333:Insulin Resistance / Q000208:ethnology* / Q000502:physiology*; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000208:ethnology*; D065626:Non-alcoholic Fatty Liver Disease; D009749:Nutrition Surveys; D011237:Predictive Value of Tests; D012016:Reference Values; D014280:Triglycerides / Q000097:blood; D014481:United States; D044465:White People
D014280:Triglycerides; D000410:Alanine Transaminase
inflammation; metabolic syndrome; racial/ethnic difference; visceral obesity