Endocrine Abstracts

Three premenopausal patients presented with high isolated testosterone without symptoms of androgen excess or illicit drug use.

Case 1: A 22-year-old female presented with daily vaginal bleeds having been on depot injections of progesterone with supplementary norethisterone. Testosterone was 14.5 nmol/l with suppressed gonadotrophins (LH <0.1 IU/l, FSH 0.2 IU/l, oestradiol <19 pmol/l). Her norethisterone was stopped. A repeat biochemical profile after 3 weeks was normal (testosterone 0.8 nmol/l, FSH 4.1 IU/l, LH 3.4 IU/l, oestradiol 230 pmol/l).

Case 2: A 43-year-old female presented with a 3 week history of prolonged menstrual bleeding. She commenced norethisterone; 2 days later testosterone was 7.6 nmol/l, SHBG 66.9 nmol/l, free androgen index 11.36, LH 0.4 IU/l, FSH 1.2 IU/l, oestradiol 198 pmol/l. Repeat testing 12 days after stopping norethisterone was normal: testosterone 0.8 nmol/l, 85.4 nmol/l, free androgen index 0.94, FSH 6.3 IU/l, LH 5.5 IU/l, oestradiol 839 pmol/l, cortisol 302 nmol/l).

Case 3: A 20-year-old female with dysmenorrhoea on the oral contraceptive pill commenced norethisterone with resolution of her symptoms and amenorrhoea. She took lamotrigine for epilepsy but denied other medications. Initial testosterone was elevated: 7.7 nmol/l, SHBG 9.4 nmol/l, free androgen index 81.91, FSH 1.3 IU/l, LH <0.1 IU/l. After 3 weeks, her biochemistry had improved: 17OHP <1 nmol/l, cortisol 169 pmol/l, FSH 0.6 IU/l, LH <0.1 IU/l, testosterone 4.2 nmol/l, SHBG 10.1 nmol/l, free androgen index 41.58. After a further 2 weeks her testosterone was normal (0.9 nmol/l).

All patients had elevated testosterone associated with norethisterone use, which normalised 19–41 days after norethisterone was stopped. Norethisterone is metabolised to 19-norandrosterone (as is nandrolone) via 5-α-reductase but has only weak androgenic activity. We hypothesise that 19-norandrosterone interferes the Roche Modular E170 Testosterone II assay used, giving a falsely elevated testosterone.