The association between fasting hyperbilirubinaemia and serum non-esterified fatty acids in man

A cohort study of serum bilirubin levels and incident non-alcoholic fatty liver disease in middle aged Korean workers

Background

Serum bilirubin may have potent antioxidant and cytoprotective effects. Serum bilirubin levels are inversely associated with several cardiovascular and metabolic endpoints, but their association with nonalcoholic fatty liver disease (NAFLD) has not been investigated except for a single cross-sectional study in a pediatric population. We assessed the prospective association between serum bilirubin concentrations (total, direct, and indirect) and the risk for NAFLD.

Methods and Findings

We performed a cohort study in 5,900 Korean men, 30 to 59 years of age, with no evidence of liver disease and no major risk factors for liver disease at baseline. Study participants were followed in annual or biennial health examinations between 2002 and 2009. The presence of fatty liver was determined at each visit by ultrasonography. We observed 1,938 incident cases of NAFLD during 28,101.8 person-years of follow-up. Increasing levels of serum direct bilirubin were progressively associated with a decreasing incidence of NAFLD. In age-adjusted models, the hazard ratio for NAFLD comparing the highest to the lowest quartile of serum direct bilirubin levels was 0.61 (95% CI 0.54–0.68). The association persisted after adjusting for multiple metabolic parameters (hazard ratio comparing the highest to the lowest quartile 0.86, 95% CI 0.76–0.98; P trend = 0.039). Neither serum total nor indirect bilirubin levels were significantly associated with the incidence of NAFLD.

Conclusions

In this large prospective study, higher serum direct bilirubin levels were significantly associated with a lower risk of developing NAFLD, even adjusting for a variety of metabolic parameters. Further research is needed to elucidate the mechanisms underlying this association and to establish the role of serum direct bilirubin as a marker for NAFLD risk.

Hematological and blood biochemical effects of fasting and subsequent oral administration of endotoxin in prepubertal gifts

The main objective of the present study was to investigate the effects of short-term fasting in gilts on endocrinological and blood biochemical parameters and, further, the effects of subsequent oral endotoxin (ET) administration. Group 1 was fasted for 30 h and then received feed with ET added. Group 2 was fasted for 30 h but received standard feed at refeeding. In group 3, gilts were fed every 6 h for 30 h. The major effects of fasting were: gradually increased concentration of plasma prostaglandin F2 alpha metabolite, serum total bilirubin, serum free fatty acids, and decreased serum glucose. The values were normalized within 1-4 h of refeeding. Twelve hours after refeeding, the ET-refed gilts showed higher levels of serum total bile acids and polymorphonuclear leukocytes than those in group 2. It is possible that the observed changes during fasting reflect either an increased intestinal uptake of naturally present endotoxin or a reduced endotoxin detoxifying capacity of the liver. The increased bile acid concentration and polymorphonuclear leukocyte count following refeeding with ET-feed may indicate that orally administered ET is to some extent absorbed from the gut.

Plasma bilirubin and serum free fatty acids after myocardial infarction

Fasting concentrations of plasma bilirubin were measured in 34 patients on admission to hospital and daily for 7 days after uncomplicated myocardial infarction. Mean concentrations increased significantly to reach maximum levels on the second day after admission, and fell during the following 5 days to reach the admission level by the 7th day. Unconjugated bilirubin accounted for most of this rise. Serum concentrations of free fatty acids (FFA), measured simultaneously in 12 patients, were highest within 12 hr of the onset of symptoms, when their level was significantly higher than at any time after the first day. It is suggested that the transient hyperbilirubinaemia after uncomplicated myocardial infarction is frequent and may result from interference by FFA with bilirubin metabolism.