What is the diagnosis for a 22-year-old female with amenorrhea (missed periods), negative pregnancy test, normal laboratory results, hyperandrogenism (elevated testosterone) of 0.75, normal prolactin level of 13.40, and normal Follicle-Stimulating Hormone (FSH) level of 3.9, not taking birth control, and a normal Papanicolaou (PAP) test result?

Differential Diagnosis for 22 F with Missed Periods

Single Most Likely Diagnosis

• Polycystic Ovary Syndrome (PCOS): Although the testosterone level is not significantly elevated, PCOS can present with normal testosterone levels. The patient's age, missed periods, and normal prolactin and FSH levels make PCOS a likely diagnosis. However, a more detailed evaluation, including ultrasound and further hormonal testing, would be necessary for a definitive diagnosis.

Other Likely Diagnoses

• Hypothalamic Amenorrhea: This condition is characterized by decreased gonadotropin-releasing hormone (GnRH) secretion, leading to low FSH and LH levels. Although the FSH level is within the normal range, stress, weight changes, or excessive exercise could be contributing factors.
• Thyroid Dysfunction: Although not directly indicated by the provided labs, thyroid disorders can cause menstrual irregularities. It would be essential to check thyroid-stimulating hormone (TSH) levels to rule out hypothyroidism or hyperthyroidism.
• Premature Ovarian Insufficiency (POI): Although less common in a 22-year-old, POI could be a consideration, especially if there's a family history. However, the FSH level is not elevated, making this diagnosis less likely.

Do Not Miss Diagnoses

• Pituitary Tumor: Although the prolactin level is within the normal range, a prolactinoma or other pituitary tumor could be present, causing menstrual irregularities. Imaging studies, such as an MRI, would be necessary to rule out a pituitary tumor.
• Adrenal Disorders: Certain adrenal disorders, such as congenital adrenal hyperplasia, can cause menstrual irregularities and should be considered, especially if there are other symptoms like hirsutism or virilization.

Rare Diagnoses

• Androgen Insensitivity Syndrome: A rare condition where the body is unable to respond to androgens, leading to primary amenorrhea.
• Gonadal Dysgenesis: A rare condition characterized by abnormal gonadal development, which can cause primary amenorrhea.
• Autoimmune Disorders: Certain autoimmune disorders, such as autoimmune oophoritis, can cause ovarian dysfunction and menstrual irregularities. However, these conditions are rare and would require further evaluation to diagnose.