Testicular dysfunction in men with primary hypothyroidism; reversal of hypogonadotrophic hypogonadism with replacement thyroxine.
OBJECTIVE
Primary hypothyroidism can cause disturbances in normal gonadal function. The aim of this study was to investigate the relationship in men between hypogonadism and primary hypothyroidism and the extent to which free and total testosterone levels rose after introduction of replacement thyroxine.


METHODS
Paired study of patients in a hypothyroid and thyroxine treated state.


METHODS
Ten men with primary hypothyroidism.


METHODS
Free and total testosterone, gonadotrophin and prolactin levels before and after thyroxine replacement therapy.


RESULTS
Low free testosterone levels (161 +/- 62 pmol/l) demonstrated at the time the men were hypothyroid rose significantly with the commencement of thyroxine replacement (315 +/- 141 pmol/l; P < 0.001). Gonadotrophin levels were not elevated consistent with hypogonadotrophic hypogonadism. Hyperprolactinaemia, which can occur in primary hypothyroidism and cause hypogonadotrophic hypogonadism, was not present in the majority of these patients. However a reduction in prolactin level was evident with thyroxine replacement and a rise in free testosterone levels.


CONCLUSIONS
This suggests an effect of hypothyroidism on gonadotrophin secretion at the level of the hypothalamus-pituitary, either directly or through modulation of prolactin secretion. Low free testosterone may also be a contributing factor to some of the symptoms and signs of hypothyroidism in men.
Donnelly
P
P
Royal Prince Alfred Hospital, Camperdown; Liverpool District Hospital; Prince of Wales Hospital, Sydney, Australia.
White
C
C
D000328:Adult; D000704:Analysis of Variance; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007006:Hypogonadism / Q000097:blood / Q000188:drug therapy* / Q000209:etiology*; D007037:Hypothyroidism / Q000097:blood / Q000150:complications* / Q000188:drug therapy*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000097:blood; D013739:Testosterone / Q000097:blood; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use*
D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013974:Thyroxine