Calculating Free Testosterone in Men with Elevated SHBG

Understanding Free Testosterone Calculation Methods

The Vermeulen equation is commonly used to calculate free testosterone from total testosterone and sex hormone-binding globulin measurements, as recommended by the Endocrine Society 1, 2.

Direct measurement of free testosterone using equilibrium dialysis is considered the gold standard and provides more accurate results than calculated methods, especially in men with elevated SHBG, according to the American Gastroenterological Association 3, 5.
Morning serum samples should be used for testosterone assessment, as there is significant diurnal variation in levels, as noted by the European Society of Gastroenterology 4, 5.

For men with conditions that can affect SHBG levels, such as obesity, free testosterone measured by equilibrium dialysis provides more accurate results than calculated methods, as suggested by the American Gastroenterological Association 3, 5.
When evaluating testosterone status in men with abnormal SHBG levels, clinical symptoms should be considered alongside laboratory values, according to the American Diabetes Association 6.
If hypogonadism is suspected despite normal calculated free testosterone, further evaluation including luteinizing hormone and follicle-stimulating hormone measurements may be warranted, as recommended by the American Gastroenterological Association 5.