Editing Male Reproductive Physiology (section)

=== <span style="color:#ff0000">Circulation ===
* '''<span style="color:#ff0000">Circulates in bound (98%) and free (2%) form'''
*'''<span style="color:#ff0000">Binding proteins (3):'''
*# '''<span style="color:#ff0000">Albumin (50%, loosely-bound)'''
*#'''<span style="color:#ff0000">Sex hormone-binding globulin ([SHBG], 44%, tightly-bound)''' 
*#*Produced in the liver
*#'''<span style="color:#ff0000">Corticotropin-binding globulin (4%, loosely-bound)'''
*'''<span style="color:#ff0000">The free and loosely-bound (albumin, corticortropin-binding) testosterone fractions combined are known as bioavailable testosterone<span style="color:#ff0000">'''
**<span style="color:#ff0000">'''Only bioavailable testosterone can enter cells and have an effect on the androgen receptor.'''
**Free and total testosterone measurements are most accurate when done by equilibrium dialysis but in the absence of this assay, they can be calculated from total testosterone, SHBG and albumin.
** <span style="color:#ff0000">'''Serum testosterone levels <300 ng/dL considered low'''
**Calculated free testosterone <6.5 ng/dL considered low
**Intratesticular testosterone levels are 50-100x those of the circulating serum levels and are necessary for appropriate spermatogenic function.
*'''SHBG'''
**'''<span style="color:#ff0000">Conditions associated with decreased SHBG (so expect higher proportion of bioavailable testosterone for same total testosterone level)'''
**#'''<span style="color:#ff0000">Obesity'''
**#'''<span style="color:#ff0000">Nephrotic syndrome''' 
**# '''<span style="color:#ff0000">Hypothyroidism'''
**#'''<span style="color:#ff0000">Use of glucocorticoids, progestins, and androgenic steroids'''
**#'''<span style="color:#ff0000">Acromegaly''' 
**#'''<span style="color:#ff0000">Diabetes mellitus'''
**'''<span style="color:#ff0000">Conditions associated with increased SHBG [so expect lower proportion of bioavailable testosterone for same total testosterone level]'''
**#'''<span style="color:#ff0000">Aging''' 
**#'''<span style="color:#ff0000">Hepatitis and cirrhosis/liver failure'''
**#'''<span style="color:#ff0000">Hyperthyroidism'''
**#'''<span style="color:#ff0000">Use of anticonvulsants'''
**#'''<span style="color:#ff0000">Use of estrogens'''
**#'''<span style="color:#ff0000">HIV'''