ADIPOQ and hepatocellular carcinoma: Stratification by the sample source revealed HCC group had significantly higher AdipoQ levels than CFC group in the source of plasma (SMD = 0.23, 95% CI (0.08, 0.38), P = 0.003), but not in the source of serum (SMD = 0.23, 95% CI (− 0.51, 0.97), P = 0.540).