title: The Effect of Serum Vitamin D on Serum ALT Levels in Healthy Individuals.
abstract: Several studies have examined the relationship between vitamin D (VD) and liver disease but none have explored this relationship in adults with normal liver enzymes. Our aim was to explore an independent association of VD with alanine aminotransferase (ALT) in a large sample of the US adults with liver enzymes in normal range (≤39 U/L).
  
  
  
  We used the continuous National Health and Nutrition Examination Survey from 2001 to 2006. We excluded individuals with serum ALT>39 U/L. We built linear regression models to estimate unadjusted and adjusted (age, sex, race, diabetes, hypertension, alcohol use, smoking, and body mass index) effect sizes, taking into account the complex probability survey design.
  
  
  
  Of the 12,155 participants, 6635 (54.6%) were women, mean±SD age was 49.9±19.4 years, VD was 21.9±9.2 ng/mL, and ALT was 20.9±6.9 U/L. In unadjusted analysis, VD was significantly associated with serum ALT (0.02 U/L/ng/mL of VD, P=0.007). After adjustment for confounders, VD remained statistically significantly associated with serum ALT levels (0.04 U/L, P<0.001). Similarly, individuals in the highest quartile of VD had significantly higher serum levels of ALT than those in the lowest quartile (unadjusted difference=0.98 U/L, P<0.001; adjusted difference=1.21 U/L, P<0.001).
  
  
  
  We found a positive association between VD and ALT after excluding individuals with suspected active liver injury (ALT>39 U/L). The underlying mechanisms for this association are not known and needs further study.
authors.affiliation: *Department of Medicine, University of Tennessee College of Medicine at Chattanooga, Chattanooga, TN †Division of General Internal Medicine, Johns Hopkins School of Medicine, Baltimore, MD.
authors.forename: Elaine
authors.initials: E
authors.lastname: Shehata
authors.forename: Rehan
authors.initials: R
authors.lastname: Qayyum
mesh_terms: D000328:Adult; D000410:Alanine Transaminase / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012016:Reference Values; D012044:Regression Analysis; D014481:United States; D014807:Vitamin D / Q000097:blood*; D055815:Young Adult
chemical_list: D014807:Vitamin D; D000410:Alanine Transaminase