Ethnic Differences in the Link Between Insulin Resistance and Elevated ALT

Abstract

WHAT'S KNOWN ON THIS SUBJECT: Evaluating for elevations in alanine aminotransferase (ALT) is a common screening test for the presence of nonalcoholic fatty liver disease (NAFLD). NAFLD is less common among non-Hispanic blacks. Better predictors of NAFLD are needed to identify individuals in most need of screening. WHAT THIS STUDY ADDS:Relative to other ethnicities, metabolic syndrome and insulin resistance performed poorly at identifying non-Hispanic black adolescents with ALT elevations. The presence of metabolic syndrome may therefore not be an adequate trigger for NAFLD screening. Triglyceride elevations performed similarly between groups in identifying ALT elevations. abstract 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 nonHispanic black adolescents, focusing particularly on those with triglyceride elevations. Pediatrics 2013;132:e718-e726 KEY WORDS metabolic syndrome, visceral obesity, inflammation, racial/ethnic difference ABBREVIATIONS ALT-alanine aminotransferase BP-blood pressure GGT-g-glutamyl transferase HDL-C-high-density lipoprotein cholesterol HOMA-IR-homeostasis model of insulin resistance hsCRP-high-sensitivity C-reactive protein IR-insulin resistance MetS-metabolic syndrome NAFLD-nonalcoholic fatty liver disease OR-odds ratio WC-waist circumference Drs DeBoer, Wiener, and Barnes were involved in th...

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“…In addition, despite differences in body fat, Hispanic and nonHispanic black children are more insulin-resistant than non-Hispanic white children. 11,16 A similar study found that children with metabolic syndrome had lower insulin sensitivity when compared with children without any risk factors, 17 possibly representing an important indicator for the development of cardiovascular disease and type 2 diabetes mellitus. 11,17 According to Marzuillo and colleagues, 18 nonalcoholic fatty liver disease (NAFLD) has more than doubled in the last 20 years, mirroring the increase prevalence in childhood obesity and becoming the most common form of liver disease in childhood.…”