OBJECTIVES/SPECIFIC AIMS: More men than women develop urinary stones and their prevalence alters in women with menopause suggesting a steroidal influence. In men the incidence of stones is highest during July and August suggesting that environmental factors such as Vitamin D (VitD), a steroid, may affect stone formation. Previous studies have found differences in the development of stones between men and women; however, the reasons for sex differences in stone formation and type remain unclear. METHODS/STUDY POPULATION: We examined VitD levels in men and women (n = 18,753) that had no diseases based on a lack of an ICD-9 or ICD-10 code in their electronic medical record. We found that normal, healthy women had significantly higher levels of sera VitD compared to men (p = 6x10-6). We then examined whether sex differences existed for key endpoints/data from the Mayo Clinic Urinary Stone Disease (USD) Registry, which has around 1,600 urinary stone patients that are well-phenotyped according to sex, age and stone type. RESULTS/ANTICIPATED RESULTS: Control women were found to have higher sera VitD levels than men, but the sex difference no longer exists in kidney stone disease patients. When we further separated by race, we found that differences in VitD levels reappeared; this suggests that race also plays a role in sera VitD variances. DISCUSSION/SIGNIFICANCE OF IMPACT: We are developing a disease severity score, which we will use to correlate to sera VitD levels in patients according to sex, age and race. Future analyses will take into account whether subjects had VitD and calcium supplementation. This project begins to explore the mechanism behind the sex differences known to exist in urinary stone disease, which is critically needed to provide improved diagnosis and therapy for this debilitating disease.