Evaluation of alopecia often includes laboratory testing for ferritin, thyroid stimulating hormone, vitamin D, and zinc as previous studies have found associations between non-scarring alopecia and vitamin deficiencies. These studies are limited by small sample sizes, and subsequent analyses showed conflicting results. This study aims to explore laboratory abnormalities in non-scarring alopecia and examine whether supplementation is associated with increased hair growth. A total of 131 patients completed at least two visits by a hair specialist at NYU’s Faculty Group Practice. They had quantitative hair measurements taken at each visit and laboratory tests performed at the first visit. There were 20 (15.3%) patients with abnormal lab results. The most common vitamin deficiency was ferritin (6.5%). Forty-two (32%) patients received supplementations that specifically addressed their vitamin or hormone deficiency. Multivariate regression analysis showed that supplementation did not significantly impact hair density or diameter (P=0.73; P=0.96, respectively). Baseline hair density and diameter were positively associated with change in hair density and diameter, respectively (standardized coefficient [β] 0.57, P<0.01; β 0.61, P<0.01). The number of prescribed oral medications was negatively associated with change in hair diameter (β -6.60, P=0.04). Limitations of this study include the single-center, retrospective design and the short followup interval. However, our findings suggest that vitamin supplementation may not lead to improved outcomes in non-scarring alopecia, thus limiting the utility of laboratory testing. Additional large-scale prospective studies are needed to improve our management of alopecia. J Drugs Dermatol. 2021;20(7):807-809. doi:10.36849/JDD.5886.