RBP4 and hypertensive disorder: It was found that blood RBP4 levels were significantly elevated in patients with untreated essential hypertension (Solini et al., 2009; Zachariah et al., 2016; Li et al., 2019) and significantly correlated with left ventricular diastolic function (Porcar-Almela et al., 2015; Li et al., 2019).