Endocrine Abstracts

Introduction: Marked elevation of testosterone levels can be caused by tumors with hormonal hypersecretion. However, we should be aware of the relationship between thyroid and sexual hormones, including changes of SHBG.

Case report: A 48-year-old man was recommended by an urologist to endocrinological examination due to high levels of total testosterone.

CT scan of abdomen, pelvis and the pituitary did not show any abnormalities.

The patient did not complain of any problems, but after inquiry he admitted a weight loss of 15 kg during last year which he related to his effort of eating less because of obesity. Apart of that we did not find any deviations from physical normal status including thyroid palpation, skin temperature and heart rate. Laboratory tests revealed the following results: fT₄ 48 pmol/l, fT₃ 16 pmol/l, TSH 0.005 mIU/l, total testosterone 59 nmol/l and SHBG 190 nmol/l (34–66). Free androgen index was still within the normal range 31 (30–152).

Within four months of therapy by antithyroid drugs, both the levels of thyroid hormones and total testosterone returned to norm.

Conclusions: Hyperthyroidism may lead to an elevation of total testosterone in males due to an increase of hepatic synthesis of SHBG. The metabolic clearance of testosterone is also decreased and the peripheral conversion of androstendion to testosterone is increased. Despite this, the levels of free testosterone are usually normal.

The restoration of all these parameters is in most cases achieved after euthyroidism is established.

This report shows the need of judging the levels of sexual hormones in connection with the levels of thyroid hormones (and SHBG) with respect to the fact that thyroid disorders may be clinically silent.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.