The association between serum alanine aminotransferase and hypertension: A national based cross-sectional analysis among over 21 million Chinese adults.

Background: Inconsistent results were found in the association between serum alanine aminotransferase (ALT) and hypertension among population-based studies. This study evaluated the association between ALT and hypertension among Chinese reproductive-age population by utilizing registration data from National Free Pre-pregnancy Checkups Project in 2016-2017.

Methods: The 21,103,790 registered participants were eligible for analysis, including women who were 20-49 years old and men who were 20-59 years old with available data for ALT and blood pressure (BP). Logistic regression was conducted to estimate odds ratio (OR) for the association between ALT and hypertension as a binary outcome. Linear regression was used to examine the association between ALT and BP as a continuous outcome.

Results: In total, 4.21% of the participants were hypertensive, and 11.67% had elevated ALT (> 40 U/L). Hypertension prevalence was 3.63% and 8.56% among participants with normal and elevated ALT levels. A strong linear relationship was found between serum ALT levels and the odds of hypertension after adjustment for potential confounders. The multivariable-adjusted ORs for hypertension were 1, 1.22 (1.21, 1.22), 1.67 (1.65 1.68), 1.78 (1.76, 1.80), and 1.92 (1.90, 1.94) in participants with ALT levels of ≤ 20, 20.01-40, 40.01-60, 60.01-80, and > 80 U/L, respectively. Systolic and diastolic BPs rose by 1.83 and 1.20 mmHg on average, for each 20 U/L increase in ALT (P  < 0.001). The association was consistent among subgroups and tended to be stronger among populations who are overweight (body mass index ≥ 24 kg/m) (χ = 52,228, P < 0.001), alcohol drinking (χ = 100,730, P < 0.001) and cigarette smoking (χ = 105,347, P < 0.001).

Conclusions: Our cross-sectional analysis suggested a linear association between serum ALT and hypertension or BP, which indicated that abnormal liver metabolism marked by elevated serum ALT could play a role in hypertension or elevated BP condition.