Endocrine Abstracts

Hypothalamic amenorrhea is a diagnosis of exclusion. It accounts for 30% of cases of secondary amenorrhoea in women of reproductive age. It is caused by abnormal signalling between the hypothalamus and the pituitary gland due to deficient pulsatile secretion of GnRH. This reduced secretion of GnRH leads to levels of LH and FSH that are insufficient to maintain full folliculogenesis and normal ovulatory ovarian function, with consequent oestrogen deficiency. There are many causes, including poor nutrition, stress, medications or excessive exercise. 22-year-old lady with history of low BMI was referred by her GP with secondary amenorrhea. History was significant for weight loss over the past 2 years although she had made efforts to improve this recently (BMI 16 kg/m2 initially, improved to 18 kg/m2). She also described weightlifting four times per week with lengthy sessions and cardiovascular exercise in-between. She was non-smoker and denied any drug abuse. Initial evaluation showed BMI of 18 kg/m2, normal prolactin (248 mu/l) but undetectable oestradiol level <92 pmol/l alongside inappropriately low gonadotropins (LH 3 IU/l FSH 6 IU/l). Thyroid function and anterior pituitary hormone profile were otherwise normal. There were no clinical manifestations of hyperandrogenism, and biochemical androgen levels were normal. Ultrasound showed normal appearances of female reproductive organs with no signs to suggest polycystic ovarian syndrome. On review by the endocrine team, we discussed the importance of achieving healthy weight gain, reasonable fat mass compared with lean body mass and adequate BMI as best management for hypothalamic amenorrhea and directed her towards psychological services via GP. Interval laboratory evaluation showed oestradiol 239 pmol/l, testosterone 1 nmol/l, Serum prolactin 303 mU/l, LH 8 IU/l, FSH 7 mU/l. Patient had resolution of her periods with appropriate diet and weight gain and was later discharged from further follow up.

Conclusion: It is important to thoroughly exclude organic and anatomic causes of amenorrhea before establishing the diagnosis of hypothalamic amenorrhea. Optimising weight and reducing excessive exercise can be challenging and may often require co-ordinated input from psychological services, endocrinology, primary care and wider family members. Hormone replacement therapy has a role when HA is prolonged, or the underlying cause cannot be addressed.