Endocrine Abstracts

Liver dysfunction is common in patients with hyperthyroidism. The underlying mechanisms remain unclear. Predictors of liver dysfunction and recovery are controversial. The aim of this study was to assess the prevalence of elevated liver enzymes in patients with uncontrolled hyperthyroidism and to identify its predictive factors.

Methods: This is a retrospective study conducted in 131 patients with hyperthyroidism admitted in the endocrinology department of La Rabta Hospital (Tunisia) between January 2009 and December 2018. Patients with subclinical hyperthyroidism and those with controlled thyroid function under treatment were not included. Liver enzymes: Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured in all the patients at admission. Clinical and biological data were reviewed to identify factors associated with elevated liver enzymes (AST and/or ALT) using univariate and multivariate analysis.

Results: The mean patient age was 44.1±16.9 years. They were 52 men (39.7%) and 79 women (60.3%). Hyperthyroidism was related to Graves’ disease in 74.8% of cases. The mean AST level was 25.6±18.4 UI/l (normal range: 5-34). It was elevated in 16.0% of patients. The mean ALT level was 28.8±22.5 UI/l (normal range: 6-55). It was elevated in 8.4% of patients. Elevated liver enzymes (AST and/or ALT) have been observed in 18.3% of cases. FT4 levels were significantly higher in patients with elevated liver enzymes (6.0±4.2 vs 4.3±2.1 ng/dl, P=0.006). FT4 higher than 4 times normal range was associated with elevated liver enzymes (41.7% vs 19.6%, P=0.02, OR [95%CI] = 2.9 [1.2-7.4]). Age, gender, smoking status, BMI, etiology of hyperthyroidism, and anti-TSH receptor antibody levels were not associated with elevated liver enzymes. After adjustment for age and gender, FT4 level higher than 4 times the normal range remains an independent parameter associated with elevated liver enzymes (P=0,05; ORa [95%CI]= 2.5 [1.0-6.7]).

Conclusion: Elevated liver enzymes are common in hyperthyroidism. The biological severity of hyperthyroidism seems to be the main predictive factor of this liver dysfunction.