Testosterone
Testosterone is used to help diagnose erectile dysfunction, infertility, early or delayed puberty and other disorders.
Free testosterone
Most of the testosterone in the blood circulates bound to proteins, one of which is sex hormone binding globulin (SHBG). Only a small amount of testosterone is not bound and is ‘free’. Free testosterone provides a measure of the amount of testosterone available to tissues.
SHBG or Sex hormone binding globulin
The amount of free testosterone is affected by the levels of SHBG. High levels of SHBG may be caused by cirrhosis of the liver, anti-convulsant therapy, oestrogen therapy and hyperthyroidism. Low levels are present in hypothyroidism, androgen use, nephritic syndrome, polycystic ovarian syndrome and obesity.
Prolactin (PRL)
Prolactin regulates galactorrhoea (milk production). Prolactinoma (an overgrowth of the gland that secretes prolactin) may be related to visual disturbances and headaches. Prolactin levels are also part of investigation for female and male infertility; for follow up of low testosterone in men.