ODP431 Adiposity in menstrual dysfunction and the role of laboratory testing in diagnosis

Adiposity significantly contributes to reproductive function. Whereas lower body weight is strongly associated with increased risk of functional hypothalamic amenorrhea (FHA), the relationship between BMI and the timing of menopause is poorly understood. Recent studies of self-reported data suggest women with BMI<18.5kg/mg 2 have a significantly higher risk of menopause before age 45 years. However, without confirmatory testing, there is the possibility of misdiagnosis of menopause given the prevalence of FHA in low-weight women. Although FHA and menopause are clinically identical, laboratory evaluation could potentially aid in differentiating the two entities, as menopause is characterized by high gonadotropin levels, whereas FHA is characterized by low-normal gonadotropin levels. Given the increased morbidity and mortality associated with early age of menopause, this distinction is clinically important. We sought to identify age of menopause in low-weight women using clinically available data at a large, academic health system. We hypothesized that women with a BMI<18.5kg/m 2 would have a lower age of menopause but that confirmatory diagnostic testing to differentiate menopause from FHA would be infrequently performed. The study was conducted by retrospective chart review of the electronic medical records of 3,000 women >50 years of age and BMI<18.5kg/m 2 . After exclusion of individuals with no date of menopause, BMI>18.5 kg/m 2 at the menopausal transition and history of known cause of early menopause, 239 charts were included in the analysis. Participants had a median BMI of 17.7kg/m 2 at the final menstrual period (FMP). Median age at the FMP in all low weight women with BMI<18.5kg/m 2 was 51 years. There was a positive correlation between age of the FMP and BMI (rho=0.13, p=0. 04). When stratified by BMI, age of the FMP decreased with decreasing BMI. For women with a BMI of 18-18.49kg/m 2, FMP occurred at a median age of 51 years; for women with a BMI of 16-17.99 kg/m 2, FMP occurred at a median age of 50 years; and for women with BMI<16kg/m 2, FMP occurred at a median age of 48 years. Only 30 women (12.6%) included in the study had an FSH level measured after diagnosis of menopause and eight of these women (26.67%) had an FSH<18 (range: 0.7-14.7 IU/mL), which is lower than expected for menopause. Therefore, these data, obtained from clinical data rather than self-report, provide further evidence that low-BMI is associated with lower age of menopause. Although current societal guidelines do not recommend diagnostic evaluation of menopause in women older than 45 years, our data suggest that there is a risk of misclassifying FHA as menopause in low-weight women if diagnostic evaluation is not performed. Further studies are necessary to determine the role and clinical benefit of diagnostic confirmation of menopause in low-weight women with amenorrhea. Presentation: No date and time listed