Endocrine Abstracts

Introduction: Testosterone <5nmol/l is commonly seen in conditions such as PCOS however when testosterone is >5nmol/l, concerns start to rise about more sinister causes. Here, we present a case of a female who was referred to clinic with testosterone >5mmol/l

Case: A 32 year old presented to the GP with a heavier than usual menstrual period. For an unknown reason, the GP checked testosterone, which came back as 8.5nmol/l (0.5-2.6) and 10.3nmol/l on repeat testing. When taking the clinical historyin clinic, there were no signs or symptoms of hyperandrogenism and periods were regular. The patient took no regular medications including no contraception and denied over-the-counter/herbal remedies. Testosterone previously checked when the patient was 23 years old was 1.7nmol/Lessentially excluding androgen insensitivity. Testosterone was remeasured and was 9.4nmol/l. 17-OHP, androstenedione and DHEA-S were normal. A testosterone producing tumour was suspected. MRI of the ovaries and adrenals were urgently requested in which only polycystic ovaries and adenomyosis were seen. Given the lack of signs or symptoms of high testosterone or PCOS, assay interference was suspected so blood was sent to other laboratories for analysis. Whilst awaiting these results, a dexamethasone suppression test was arranged and testosterone fell from 8.5nmol/l to 4.7nmol/l. Our local laboratory uses a testosterone immunoassay. Testing on another immunoassay platform at another laboratory revealed a testosterone result of 13.3nmol/l (0.3-1.7). The same sample, when tested using liquid chromatography mass spectrometry gave a result of 1.9nmol/l (0.2-2.1) confirming assay interference. The patient denied contact with animals, although did eventually reveal taking a pro-collagen supplement containing biotin.

Learning point: Having an understanding of which assays are used in your local laboratory is essential when interpreting test results. When signs and symptoms do not match the results, think about assay interference.