Abstract Objective Few studies have addressed serum levels of hypothalamic hormones, as a consequence of sports-related concussion, in concussed, female adolescent athletes. Methods Female athletes, ages 14–18, were assigned to two study groups: 1) 18 diagnosed with a sports-related concussion (SRC) and evaluated within 7 days of injury, and 2) 18 healthy participants matched on age, education, and sport. Participants self-reported menstrual cycle status, with Days 1–15 of the menstrual cycle corresponding to the Follicular phase and days >15 to the Luteal phase. Blood samples were drawn for Plasma concentration measurement of follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), adrenocorticotropin hormone (ACTH), prolactin, growth hormone (GH) and progesterone. Using progesterone plasma concentration, <=2 ng/mL corresponding to the Follicular phase and > 2 ng/mL corresponding to the Luteal phase. Results Across both groups, there was agreement between self-reported and progesterone plasma concentrations menstrual cycle Follicular (71.4%) or Luteal phase (52.9%) [X2(1) = 2.33, p = 0.13, phi = 0.25] in identifying menstrual cycle phases. Within the non-concussed controls, there was 90% agreement for Follicular phase and only 33.3% agreement for Luteal phase [X2(1) = 1.55, p = 0.30, phi = 0.29], and for the concussed athletes there was 54.5% agreement for Follicular phase and 75% agreement for Luteal phase [X2(1) = 1.66, p = 0.35, phi = 0.30] Conclusions We provide preliminary evidence of disruption of the hypothalamic–pituitary-axis (HPA) following mTBI as there was a 90% agreement between self-reported follicular phase and follicular phase determined by Progesterone levels for non-concussed females as compared to 54% agreement between the same measures for concussed females.