Editing Testosterone Deficiency (2018) (section)

== Pathophysiology ==

=== Classification ===
*'''<span style="color:#ff0000">Causes classified as primary vs. secondary</span>'''
** '''<span style="color:#ff0000">Primary: caused by testicular failure</span>'''
** '''<span style="color:#ff0000">Secondary: caused by the disruption at the hypothalamic–pituitary–gonadal (HPG) axis level</span>'''

=== Primary hypogonadism ===
* '''<span style="color:#ff0000">Primary (hypergonadotropic hypogonadism) causes (5):</span>'''
*# '''<span style="color:#ff0000">Congenital causes (</span><span style="color:#0000ff">DUNKY XX</span><span style="color:#ff0000">):</span>'''
*## '''<span style="color:#0000ff">D</span><span style="color:#ff0000">own syndrone</span>'''
*## '''<span style="color:#0000ff">U</span><span style="color:#ff0000">ndescended testis</span>'''
*## '''<span style="color:#0000ff">N</span><span style="color:#ff0000">oonan’s syndrome</span>'''
*## '''<span style="color:#0000ff">K</span><span style="color:#ff0000">leinfelters syndrome</span>''' 
*## '''<span style="color:#0000ff">Y</span><span style="color:#ff0000">-microdeletions</span>'''
*## '''<span style="color:#0000ff">XX<span style="color:#ff0000">-male</span>'''
*# '''<span style="color:#ff0000">Iatrogenic causes (e.g., bilateral orchiectomy, testicular radiation, chemotherapy)</span>'''
*# '''<span style="color:#ff0000">Testicular trauma</span>'''
*# '''<span style="color:#ff0000">Infection (orchitis)</span>'''
*# '''<span style="color:#ff0000">Auto-immune</span>'''

=== Secondary hypogonadism ===
*'''<span style="color:#ff0000">Secondary (hypogonadotropic hypogonadism) causes (8):</span>'''
*# '''<span style="color:#ff0000">Congenital causes (e.g. Kallman syndrome (congenital deficiency of GnRH))</span>'''
*# '''<span style="color:#ff0000">Pituitary or suprasellar tumors</span>'''
*# '''<span style="color:#ff0000">Pituitary infiltrative disorders (e.g., hemochromatosis, tuberculosis, sarcoidosis, histiocytosis)</span>'''
*# '''<span style="color:#ff0000">Pituitary apoplexy</span>'''
*# '''<span style="color:#ff0000">Medications (i.e. chronic opioid exposure)</span>'''
*# '''<span style="color:#ff0000">Hyperprolactinemia</span>'''
*# '''<span style="color:#ff0000">Severe chronic illness</span>'''
*# '''<span style="color:#ff0000">Systemic illnesses associated with AD:</span>'''
*#*'''Diabetes'''
*#*'''Obesity'''
*#*'''HIV'''
*#*'''Myocardial infarction'''
*#*'''Stroke'''
*#*'''COPD'''
*#*'''Respiratory illness'''
*#*'''Cancer'''
*#*'''Sepsis'''
*#*'''Chronic liver disease'''
*#*'''Chronic kidney disease;''' renal transplantation appears to reverse the hormonal abnormalities associated with ESRD
*#*'''Rheumatoid arthritis'''
*#*'''Burn injury'''
*#*'''Traumatic brain injury'''
*#*'''Surgical stress'''