MON-266 The Association Between Prolactinomas and Weight Gain

Abstract

Introduction: The prevalence of obesity is increasing worldwide and treatment remains challenging. Certain endocrine disorders may contribute to weight gain. These are important to recognize as treatment may have beneficial impact on weight. Studies have reported an increased prevalence of obesity in patients with prolactinomas. While several studies have examined the association between weight gain and prolactinomas, the results are conflicting. Therefore, the aim of this study was to determine if BMI is higher among those with a prolactinoma compared to those without.

Methods: We identified all patients ≥18 years of age referred to endocrinology between 2008–2018 with a newly diagnosed prolactinoma (defined as a prolactin levels ≥40 ng/ml on 2 separate occasions and a pituitary adenoma evident on MRI without secondary causes for hyperprolactinemia). We extracted the following variables from the medical record: patient demographics, presenting symptoms, prolactin level and tumor size at diagnosis. Comparative data was obtained from the National Health and Nutrition Examination Survey (NHANES) 2015–2016, from which we included only those ≥18 years of age who had BMI data.

Results: In total 34 patients with a newly diagnosed prolactinoma (female: 27 /34, 79%, mean age at diagnosis: 35.4 ± 10.7 years) met inclusion criteria. The majority of patients (23/34, 68 %) had microadenomas defined as <1cm. The median prolactin level at diagnosis was 103.3 (IQR 51.3- 249.25). Although the most common presenting symptoms were those consistent with hypogonadism (27/34, 79%) and galactorrhea (16/34, 47%), 1/3 patients also described weight gain. In comparison, 5662 individuals from NHANES (48 ± 18 years, female: 2955/5662, 52%) reported their BMIs. BMI was significantly increased among those with a prolactinoma compared to survey population [median BMI 30.9 kg/m2 (IQR, 24.9- 39) vs 28.3 kg/m2 (24.3- 33), P= 0.02]. This difference persisted even when adjusted for age and sex (P= 0.0002). In addition the prevalence of class II obesity (BMI ≥35 kg/m2) was higher in those with a prolactinoma compared to survey population (38% vs 18%, P=0.005). Among prolactinoma patients, there was a correlation between BMI and log-transformed prolactin levels (R2= 0.24, P=0.003).

Conclusion: Weight gain is a presenting symptom for many patients with a newly diagnosed prolactinoma. When compared to a large cohort of adults in the US, those with a prolactinoma have higher BMI and an increased prevalence of class II obesity. Based on the correlation between BMI and log-transformed prolactin levels, we hypothesize that this weight difference may be related to hyperprolactinemia. These findings suggest that, in the appropriate context, hyperprolactinemia should be considered when a patient presents with weight gain.