Editing Testosterone Deficiency (2018) (section)

=== Laboratory ===
# '''<span style="color:#ff0000">Confirmation of low testosterone</span>'''
#* '''<span style="color:#ff0000">Morning total testosterone level < 300 ng/dL</span> is considered low'''
#** '''Total testosterone can be measured by 3 methods:''' 
#***'''Liquid chromatography/tandem mass spectrometry (preferred, when possible)'''
#***'''Radioimmunoassay'''
#***'''Immunometric assay'''
#**** Significant variations among assay techniques and among different laboratories.
#**** The same laboratory with the same method/instrumentation should be used for serial total testosterone measurement.
#** '''<span style="color:#ff0000">Free testosterone measurements are not recommended as the primary diagnostic method for testosterone deficiency</span>'''
#*** Some have advocated that free testosterone should be the primary measure used to define testosterone deficiency since the free testosterone fraction is believed to be the most biologically active component. However''', direct measurement of free testosterone is unreliable, time-consuming and labour intensive'''. '''Indirect measurement''' (calculation-derived) of free testosterone is more commonly used, however there is '''considerable variation''' in total testosterone assays as well as the clinical conditions that affect serum albumin and SHBG, all of which impact this measurement.
#*** '''Free testosterone may have a place in the diagnosis of testosterone deficiency in highly symptomatic patients with total testosterone levels in the low/normal or equivocal range'''
#** While a cut-off of total testosterone < 300 ng/dL is considered low, in clinical practice, there are men with levels >300 ng/dL who are highly symptomatic and who have experienced improvement with testosterone therapy
#* '''<span style="color:#ff0000">Diagnosis of low testosterone should be made only after 2 total testosterone measurements are taken on separate occasions with both tests being conducted in an early morning</span>'''
#** Serum testosterone levels peak in the morning and vary significantly as a result of circadian and circannual rhythm
#** No evidence indicating what the optimal time interval should be between the separate tests
#** If a patient’s first test is <300 ng/dL and the second test is normal, the clinician should use his or her judgment to determine if a third test is to be used as a control
#** Fasting is not needed prior to testosterone testing
#* '''<span style="color:#ff0000">Due to associations with low testosterone, even in the absence of symptoms or signs associated with testosterone deficiency, consider measuring total testosterone in patients with a history of (11):</span>'''
#*# '''<span style="color:#ff0000">Diabetes</span>'''
#*# '''<span style="color:#ff0000">Obesity</span>''' (BMI ≥30) or who have increased waist circumference (>40 inches)
#*# '''<span style="color:#ff0000">HIV/AIDS</span>'''
#*# '''<span style="color:#ff0000">Male infertility</span>'''
#*# '''<span style="color:#ff0000">Exposure to chemotherapy</span>'''
#*# '''<span style="color:#ff0000">Exposure to testicular radiation</span>'''
#*# '''<span style="color:#ff0000">Chronic narcotic use</span>'''
#*# '''<span style="color:#ff0000">Chronic corticosteroid use</span>'''
#*# '''<span style="color:#ff0000">Pituitary dysfunction</span>'''
#*# '''<span style="color:#ff0000">Unexplained anemia</span>'''
#*# '''<span style="color:#ff0000">Bone density loss</span>'''