Abstract EP41: Relationship Between Body Mass Index And Low Total Bilirubin In US Adults

Background: Low total bilirubin (TBili) is associated with increased cardiovascular risk, in part mediated by adipose tissue-related hormones. determined whether excess adiposity (measured by BMI) is associated with low TBili levels. Methods: Our study population consisted of 14,129 (6,902 male and 7,227 non-pregnant female) adults aged ≥20 years from the 1999-2018 National Health and Nutrition Examination Surveys. Participants with elevated liver enzymes (AST>80 or ALT >112 IU/L; AST/ALT >5), excessive alcohol consumption (>20 drinks/week for males; >10 for females), iron overload (transferrin >50%), anemia (hemoglobin<12 g/dl if female; <13 g/dl if male), elevated TBili (≥1.2 mg/dl), low albumin (<3.5 g/dl), or positive hepatitis B/C serology were excluded. We categorized measured BMI into 7 categories (<18.5, 18.5-22.9, 23.0-24.9, 25.0-27.4, 27.5-29.9, 30-34.9, ≥35). Low TBili, our primary outcome, was defined as <0.4 mg/dl for both males and females. We used sex-stratified multivariable logistic regression, sequentially adjusting for demographics, cardiometabolic factors, and liver function. Results: Among 14,129 adults (mean age [SD] of 47 [15] years, 51% female, 69% White), nearly 32% had BMI ≥30. Both males and females with BMI ≥30 had >50% odds of low TBili compared to a BMI of 23-24.9, even after adjustment for covariates (Table). There was no significant association between overweight range BMIs and low TBili. Adjustment for serum albumin most significantly attenuated the associations between obese-range BMIs and low TBili, especially in males. Further classifying each BMI category into high and normal waist circumference (WC;<88cm for female, <102cm for male) groups revealed that high WC individuals, even with BMI of 23-24.9, had increased odds of low TBili (OR [95% CI]: 2.35 [1.40, 3.94]). Conclusions: Obese BMI is associated with higher likelihood of low TBili. Longitudinal studies are needed to determine directionality of association and risk of downstream cardiovascular disease.