Determinants of alanine aminotransferase levels in a large population from Southern Italy: relationship between alanine aminotransferase and age

BACKGROUND: Determinants of alanine aminotransferase levels have never been investigated in real-life settings. The relationship between alanine aminotransferase and age remains controversial. We evaluated epidemiological, anthropometric, and metabolic factors associated with alanine aminotransferase, focusing on the relationship between alanine aminotransferase and age.METHODS: A 5-year retrospective analysis was performed on data recorded by 120 general practitioners from Naples (Italy), caring for 170,000 subjects. Exclusion criteria were age <18 years, diagnosis of chronic liver disease, positive markers for viral hepatitis, alcohol abuse, and alanine aminotransferase >100UI/L.RESULTS: 44,232 subjects were enrolled (42.7% males, mean age 56±18 years). Alanine aminotransferase showed independent direct associations with body mass index, glycaemia, cholesterol, and triglycerides (p<0.001), and inverse associations with high-density lipoprotein cholesterol (p<0.001) and creatinine (p<0.01). The relationship between alanine aminotransferase and age was better expressed by polynomial regression (r=0.18, p<0.001), creating an inverted parabola. Mean alanine aminotransferase increased until the third decade in males and the fifth in females, with a subsequent progressive decrease in both genders. The inverse association between alanine aminotransferase and age in older subjects was independent from metabolic factors.CONCLUSIONS: This real-life setting study, supports the concept that dysmetabolism is a strong determinant of liver injury. Based on our data, a reduction of the standard upper limit of normal alanine aminotransferase should be considered for older subjects