medwireNews: Researchers report that metabolic abnormalities begin to increase at levels of liver fat commonly regarded as normal.
The study involved the full cohort of the Dallas Heart Study who had magnetic resonance spectroscopy (MRS) measurements of liver fat, totaling 2287 people.
Presenting the findings at the 82nd ADA Scientific Sessions in New Orleans, Louisiana, Minhda Le (University of Texas Southwestern Medical Center, Dallas, USA) noted that data from 345 “low-risk” participants of this cohort had previously been used to define an MRS cutoff of 5% to signify abnormal levels of liver fat, but subsequent studies cast doubt on this definition.
Le said that the original study did not account for factors such as abnormal fat distribution and insulin resistance, and the BMI cutoff of 25 kg/m2 may have been too high in this multiethnic cohort.
She added that the 5.6% cutoff for the 95th percentile of liver fat in the subgroup was in fact “right dab in the middle of quintile 4” based on the full cohort in the current study.
Going from lower to higher quintile, people were older, more likely to be male, less often non-Hispanic Black, and more often Hispanic.
Rates of hypertension and diabetes increased from the first to fifth quintiles, and coronary artery calcium score increased, as did fasting glucose, cholesterol and triglyceride levels, insulin resistance, and C-reactive protein levels. Adiponectin levels decreased across quintiles, whereas leptin levels rose.
Le stressed that increases in these “clinically relevant abnormalities” occurred at “well below what is currently considered normal” levels of liver fat.
The change in metabolic biomarkers “was noticeable even between the lowest two quintiles, where the upper limit of liver fat was 1.8% and 2.8%, respectively,” she said.
Liver enzyme levels also increased across the quintiles, as did measures of adiposity including BMI, waist circumference, visceral fat, and abdominal and lower body adipose tissue.
All these factors, with the exception of lower body fat, remained significantly associated with liver fat when the analysis was restricted to 1455 people with a BMI of less than 30 kg/m2.
“Our findings suggest that the presence of any liver fat may be abnormal,” concluded Le, adding that an MRS cutoff of around 2% may be optimal for defining non-alcoholic fatty liver disease.
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