['Ghrelin is a gastric peptide that has been implicated in the development of obesity and cardiovascular disease. It has been reported that ghrelin binds to lipoproteins, although the different binding patterns of acylated ghrelin (AG) and unacylated ghrelin (UAG) are still to be determined.', 'Lipoprotein fractions were generated using a self-generating iodixanol gradient. AG and UAG were measured using specific enzyme immunoassays.', 'AG bound to all lipoproteins in approximately equal concentrations (VLDL 26%, LDL 22%, HDL 23%) and was present as a plasma protein (27%). UAG bound more specifically to HDL (49%) and was present as a plasma protein (48%).'] Does circulating ghrelin exist in both lipoprotein bound and free forms?