Abstract

BACKGROUND: Recent studies suggest that shift work may cause liver dysfunction. OBJECTIVE: This study aimed to examine the relationship between different patterns of shift work and elevated level of liver enzymes. METHODS: In this cross-sectional study, 1910 workers aged 35 to 70 years were selected with simple random sampling from 9978 participants of the recruitment phase of Shahedieh PERSIAN cohort study. Level of serum liver enzymes (ALT, AST, ALP, and GGT) and ALT/AST ratio was compared between shift workers and non-shift workers, and among employees working in different patterns of shift work. Data were analyzed by SPSS (version 21.0) using Student's T test, Mann-Whitney U test, chi-square test, Kruskal Wallis test, and logistic regression. RESULTS: Among 1347 males (71) and 563 females (29) with a mean age of 40.4 +/- 7.4 years, 469 were shift workers. Fixed evening type shift was the most common (30.3) and fixed night-shift was the least common (0.9) type of shift work. The mean blood levels of liver enzymes was not significantly different between shift workers and non-shift workers. In comparison between different patterns of shift work, the mean serum level of GGT was significantly higher in individuals with slow rotating shifts than those with fixed evening shifts, rapid rotating, split and fixed 24 hour shifts (p= 0.001). After adjusting for confounding factors only elevated AST was significantly higher in shift workers. CONCLUSION: There was only a significant association between shift work and elevated AST, and no relationship was found with ALT, ALP, GGT, and ALT/AST ratio.