The association of bone turnover with the incidence and progression of nonalcoholic fatty liver disease (NAFLD) is unclear. We aimed to evaluate serum levels of bone turnover markers in relation to NAFLD and nonalcoholic hepatic steatohepatitis (NASH).

Two cohorts were involved in our study. For the first cohort, 370 participants without NAFLD were retrospectively recruited and followed up for incident NAFLD according to ultrasound. For the second cohort, 562 subjects who underwent liver biopsy were included and grouped into non-NAFLD, non-NASH or NASH according to the NASH Clinical Research Network system. The bone turnover markers osteocalcin, C-terminal telopeptide (CTX) and N-terminal propeptide of type-1 procollagen (P1NP) were measured.

Baseline osteocalcin was significantly lower in subjects who developed NAFLD (13.93 [11.03;16.39] versus 18.24 [15.45;22.47] ng/ml, P < 0.001), with a median of 26.4 months of follow-up. Low levels of osteocalcin, but not CTX or P1NP, was an independent predictor of incident NAFLD (OR 0.755 [95%CI 0.668; 0.855] P < 0.001). Moreover, the osteocalcin level was negatively associated with the degree of liver steatosis. Furthermore, subjects with NASH had significantly lower osteocalcin than non-NASH and non-NAFLD group (13.28 [10.49;16.59] versus 14.91 [12.45;18.09] versus 18.21 [15.04;22.05] ng/ml, all P < 0.001). A low osteocalcin level was an independent risk factor for NASH (OR for highest versus lowest quartile: 0.282 [0.147;0.543] P < 0.001).

Low level of osteocalcin, but not CTX or P1NP, was associated with NAFLD and NASH, indicating its potential role as an important endocrine regulator of hepatic energy metabolism.