title: Testosterone is a strong correlate of ghrelin levels in men and postmenopausal women.
abstract: OBJECTIVE
  The secretion and regulation of several hormones such as leptin and growth hormone (GH) is sexually dimorphic. Gender effects on ghrelin, a hormone involved in the regulation of GH secretion and appetite control, are controversial. Our aim was to study the relationship between plasma ghrelin and serum sex steroid hormone concentrations.
  
  
  METHODS
  Forty-five subjects (19 men, 12 premenopausal and 14 postmenopausal women) were evaluated at the Institute of Endocrinology and Metabolism, Tel Aviv Sourasky Medical Center, Israel. After an overnight fast, blood samples were collected for measurements of ghrelin, testosterone, bioavailable testosterone (BT) and estradiol. Statistical analysis was performed with adjustments for age and body mass index. Results are given as mean +/- standard deviation.
  
  
  RESULTS
  Ghrelin levels were significantly higher in women (510 +/- 489 pg/ml) than in men (319 +/- 237 pg/ml; p = 0.02). There was a positive correlation between ghrelin and both total testosterone (r = 0.5, p = 0.039) and BT (r = 0.719, p = 0.0011) in male subjects. In premenopausal women, no significant correlations were found between ghrelin and testosterone or BT (r = -0.39, p = 0.2). In contrast, ghrelin strongly and positively correlated with total testosterone (r = 0.7, p = 0.01) and BT (r = 0.821, p = 0.001) in postmenopausal women. Estradiol and ghrelin were positively correlated in the group as a whole (r = 0.356, p = 0.019), but not significantly when analyzed separately by gender.
  
  
  CONCLUSIONS
  Circulating ghrelin in humans is sexually dimorphic. Testosterone correlates positively with ghrelin levels in men and postmenopausal women.
authors.affiliation: Institute of Endocrinology, Metabolism and Hypertension, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel. greenman@tasmc.health.gov.il
authors.forename: Yona
authors.initials: Y
authors.lastname: Greenman
authors.forename: Vanessa
authors.initials: V
authors.lastname: Rouach
authors.forename: Rona
authors.initials: R
authors.lastname: Limor
authors.forename: Susan
authors.initials: S
authors.lastname: Gilad
authors.forename: Naftali
authors.initials: N
authors.lastname: Stern