Introduction: Hirsutism, the presence of terminal (coarse) hairs that appear in a male-like pattern, affects 510% of women and may cause concern for an underlying endocrine disorder or malignancy. Spironolactone compete for the androgen receptor in the hair follicle, therefore, it is frequently used in treatment of hirsutism. We report a case, in which treatment of hirsutism with Spironolactone interfered with androstenedione immunoassay and raised unnecessary concern about androgen secreting tumour.
Case: A 24-year-old lady was referred to our endocrine clinic with history of excessive hair growth since age of 16, with significant psychological impact. She had no significant past medical history, apart from coil insertion for contraception. Her initial investigations revealed normal testosterone, FSH, LH, prolactin, thyroid function. US pelvis revealed polycystic ovaries. Diagnosis of polycystic ovary syndrome was made and was subsequently treated with Spironolactone 50 mg BD, which further increased to 100 mg BD in 6 weeks time, and referred for funding for laser treatment. A repeat hormonal profile, 3 months later, showed elevated androstenedione at 59.5 nmol/l (111.5 nmol/l), with normal DHEAS, testosterone, LH, FSH, estradiol and SHBG. On repeat testing in a month, androstenedione was high at 80.5 nmol/l, while other androgens remained within normal range. Because of a very high androstenedione level, MRI adrenals and ovaries were arranged to rule out androgen producing tumour; this was unremarkable except for polycystic ovaries. At this stage, Spironolactone interference in the immunoassay of androstenedione was suspected and Spironolactone was subsequently stopped. Few months later, on a repeat testing, androstenedione level returned to normal.
Discussion: Cross reactivity of Spironolactone or its metabolites with the immunoassay of androstenedione has previously been reported. It is important, therefore, for the clinicians treating patients with Spironolactone for Hirsutism to be aware of this and communicate with biochemist to prevent any unwarranted investigations and distress for patients.