PYY is Negatively Associated with Bone Mineral Density in Exercising Women with Amenorrhea

Abstract

BACKGROUND: Peptide YY (PYY) is a satiety hormone released from the endocrine L cells of the intestine. Evidence from women with anorexia has previously demonstrated that elevated fasting PYY is associated with decreased bone mineral density (BMD). We have previously shown that exercising women with amenorrhea experience increased bone resorption related to estrogen deficiency and a decrease in bone formation related to energy deficiency. Exercising women with amenorrhea also have elevated fasting total PYY concentrations compared to eumenorrheic exercising women. PURPOSE: The purpose of this study was to assess the association between fasting total PYY and bone mineral density in non-obese premenopausal exercising women. METHODS: This was an observational study of young premenopausal exercising women (n=49). Two fasting serum samples were pooled and analyzed for total PYY. Bone mineral density and body composition were assessed by dual-energy x-ray absorptiometry. RESULTS: The women were 23.5±0.6 years, weighed 59.1±0.8 kg, and had a BMI of 21.5±0.2 kg/m2. They exercised 504±52 min/week and had a peak oxygen uptake of 48.9±1.3 ml/kg/min. Twenty of the forty-nine (20/49) women had exercise-associated menstrual cycle disturbances (EAMD). Fasting total PYY concentrations were negatively associated with total body BMD (p=0.003), lumbar spine BMD (L1-L4; p=0.011), femur neck BMD (p=0.017), and total hip BMD (p=0.008). When subjects were characterized by self-reported menstrual status, subjects deemed to have EAMD exhibited fasting total PYY concentrations that were negatively associated with total body BMD (p=0.018). In contrast, fasting total PYY concentrations of the normally menstruating women (n=29) were not associated with any BMD measures. CONCLUSION: PYY appears to be negatively associated with BMD at several sites among premenopausal, exercising women. However, more research is necessary to determine the extent to which menstrual status contributes to this association. Supported by the U.S. Department of Defense, Army Medical Research and Materiel Command (W81XWH-06-1-0145) and the National Athletic Training Association Foundation Grant #206GGP008