Objective To investigate plasma ghrelin levels in the patients with hyperthyroidism and their relation to thyroid hormones.   Methods Plasma ghrelin levels were assayed by ELISA in 20 normal subjects and 26 hyperthyroidism patients before and after medical treatment. The relationship between plasma ghrelin levels and thyroid hormones was also analyzed.   Results Plasma ghrelin levels were significantly lower in the hyperthyroidism patients than the controls [(468±136) ng/L vs

(751±212) ng/L

P0.01

]

. After Methimazole treatment for 1 month

plasma ghrelin levels

body weight and Body Mass Index (BMI) were significantly increased in hyperthyroidism patients in comparison with the controls [(468±136) ng/L vs (563±194) ng/L

(51.1±8.3) kg vs (54.2±8.1) kg

(19.8±2.4) kg/m

2

vs (20.6±2.2) kg/m

2

P0.01

]

. Two months later

plasma ghrelin levels in patients treated with Methimazole were similar to the controls [(670±214) ng/L vs (751±212) ng/L

P0.05

]

. Plasma ghrelin levels were correlated negatively with FT4 and FT3 (r=-0.43

and r=-0.37

both P0.01)

and positively with S-TSH and FAT% (r=0.29

P0.01; r=0.26

P0.05). Multiple regression analysis showed that FT4 was independent factor related to plasma Ghrelin levels.   Conclusion The circulating levels of plasma ghrelin are reduced in the patients with hyperthyroidism

but they recover after treatment. The ghrelin secretion may be suppressed by increasing thyroid hormones.