Table 2.

Characteristics of included studies.

Author. Year	Race	Participants	Number	Blood sample	Gender (Male/Female)	Age	BMI	Ghrelin
Changzhen Zhu et al., 2020	Asian	Controls	69	Serum	Unspecified	Unspecified	Unspecified	19 ± 5.8
Qi Huang-Yue et al., 2007	Asian	Controls	24	Plasma	18/6	56.7 ± 12	24.1 ± 3.8	91.4 ± 73.6
Natalie R. Pritchett et al., 2020	Asian	Controls	770	Plasma	255/515	51 ± 9	22.1 ± 2.6	1022 ± 386
Natalie R. Pritchett et al., 2020	Asian	Controls	498	Plasma	Unspecified	58 ± 9	24.8 ± 3.6	743 ± 245
Hai-Tao Wang et al., 2008	Asian	Controls	20	Plasma	8/12	40.4 ± 10.2	22.2 ± 2.2	472 ± 115.9
Anna Zub-Pokrowiecka et al., 2011	European	Controls	25	Plasma	12/13	49.3 ± 11.5	23.8 ± 2.7	302.7 ± 76.7
Krike P. et al., 2018	European	Controls	246	Plasma	Unspecified	Unspecified	Unspecified	545.9 ± 275.1
O Kemik et al., 2011	European	Controls	40	Plasma	22/18	40.4 ± 11.3	21.5 ± 2.0	1104.3 ± 201.3
Hajime Isomoto et al., 2005	Asian	Controls	39	Plasma	16/23	51	22.6	174.8 ± 125.1
Hye-Kyung Jung et al., 2022	Asian	Controls	14	Plasma	7/7	49.6 ± 5.8	22.5 ± 2.3	555.8 ± 98.4