Total Testosterone, includes:

• Bio-available T
• SHBG-bound T

Test instruction

• Diurnal variation: morning is the highest (adrenal testosterone production)
• Check on two separate occasions
• (Women: check early in menstrual cycle → follicular phase)

Conditions that affect SHBH level lead to discrepancy between TT and BioT

• Order Bio-available T or Free T in these conditions:

In female

• high TT:

  • Often elevated as a result of abnormal GnRH pulsitility → then interfere with GnRH pulsitility
  • PCOS
  • NCAH
  • Adrenal carcinoma or Ovarian cancer

• low TT:

  • Hypothalamic causes of oligo-amenorrhea (if all ovarian hormones are low)
  • POI (E, P high, T low)