Endocrine Abstracts

JOINT1952

Introduction: Hirsutism is the presence of terminal hair growth in females with a male distribution pattern. It is usually manifestation of hyperandrogenism in 80 % of the cases. Every effort should be taken to exclude polycystic ovary syndrome, endocrinopathies and rare causes before labelling it as idiopathic.

Case Report: 42-year-old female was referred by dermatologist for investigation of hirsuitism. At age 40 years, during covid pandemic, she developed localised papulopustular acne which she felt was triggered by constant mask wearing. This was treated with isotretinoin between 2021 and early 2022. After stopping this therapy, she noticed localised excessive hair growth especially affecting her upper lip and chin area impacting her quality of life. She denied other symptoms of virilization, including change of voice or growth of hair in other locations. She was otherwise healthy with no significant past medical history. Her menstrual cycles have been regular, has 3 children (no concern related to fertility). She was not on any medication or oral contraceptive pill. On examination, her BMI 21.7 with evidence of significant localised hirsuitism affecting upper lip and chin area, with some pigmentation and bumps on skin due to regular plucking. Clinically she was euthyroid, no features of Cushing’s or acromegaly. Investigations 9 am pituitary hormone profile, fasting blood glucose, HbA1c, Testosterone (Mass Spec) 1.04 (<1.89 nmol/l)Free Androgen Index (Mass Spec) 4.40 (0.73 - 6.16), DHEAS 2.93 (1.65 - 9.15 umol/l)Androstenedione 6.3 (0.9 - 7.5 nmol/L), SHBG 23.7 (20 - 155 nmol/l)were normal suggesting Isotretinoin exposure as a cause for hirsuitism.

Discussion: Isotretinoin is a synthetic vitamin A derivative used to treat nodulocystic resistant acne unresponsive to conventional treatments. While the exact mechanism of action is unknown, isotretinoin inhibits sebaceous gland function and keratinization. Most of its side effects of are self-limiting, treatable, and dose-dependent. Handful cases reported development of hirsuitism with menstrual irregularity following Isotretinoin therapy. However, to my knowledge this is the only case of isolated hirsuitism without menstrual irregularity. Studies examining the effects of oral isotretinoin on pituitary and adrenal hormones have yielded different results. It is hypothesised that isotretinoin may cause a decrease in SHBG levels and an increase in free androgens, thus leading to hirsutism and menstrual irregularity. This case highlights unusual cause of hirsuitism without menstrual irregularity. Further investigations are required to prove the mechanisms by which oral isotretinoin exerts its variable effects on the menstrual cycle, hirsutism, and hormones.