SAT-455 - Polymenorrhea as an Unusual Presentation of Non-Classic Congenital Adrenal Hyperplasia

Background: Non-classic congenital adrenal hyperplasia (NCCAH) due to partial 21-hydroxylase deficiency is an uncommon cause of menstrual abnormalities in adult women. It typically presents with hyperandrogenism and oligomenorrhea, often overlapping with polycystic ovary syndrome. We present a case of NCCAH identified during the evaluation of polymenorrhea and isolated elevation of 17-hydroxyprogesterone.

Clinical

Case: A 34-year-old woman with history of hypothyroidism presented with symptoms of polymenorrhea. Patient reported menarche starting at age 10, with regular cycles until her last childbirth which was seven years prior to presentation. She subsequently developed heavy, prolonged menses lasting 8–10 days every two weeks persisting for those seven years. She denied hirsutism, acne, alopecia, virilization, or exogenous androgen exposure. She had no history of oral contraceptive or other hormonal therapy use, and her partner was not using testosterone. She reported no fertility issues and has two children. She also noted no weight changes or Cushingoid features, including central adiposity, easy bruising, proximal muscle weakness, or uncontrolled hypertension.

Physical examination was unremarkable, with no clinical signs of hyperandrogenism. Pelvic ultrasound and endometrial biopsy revealed no structural abnormalities. Laboratory evaluation demonstrated normal total testosterone, free testosterone, FSH, LH, DHEA-S, and androstenedione levels. However, early-morning 17-hydroxyprogesterone was elevated on two separate occasions to 3725 ng/dL & 2055 ng/dL (n < 206 ng/dL). Adrenal imaging demonstrated no discrete adrenal masses.

The absence of biochemical hyperandrogenism and the presence of polymenorrhea, rather than oligomenorrhea, represented an atypical presentation of NCCAH and contributed to delayed recognition. The patient was initiated on norethindrone therapy under obstetrics and gynecology guidance, resulting in symptomatic improvement, with coordinated endocrine follow-up for long-term monitoring.

Conclusion: This case highlights an atypical presentation of non-classic congenital adrenal hyperplasia characterized by polymenorrhea and isolated elevation of 17-hydroxyprogesterone in the absence of clinical or biochemical hyperandrogenism. The mechanisms underlying polymenorrhea remain poorly understood, warranting further investigation to clarify its pathophysiology and to improve diagnostic recognition. The case also demonstrates that reliance on androgen excess alone may result in missed or delayed diagnosis. Therefore, clinicians should consider NCCAH in women with unexplained menstrual disturbances and abnormal steroid precursors, even when androgen levels are normal as accurate diagnosis is essential to guide management, avoid unnecessary testing, and inform reproductive counseling.

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