Timing

Blood should be drawn in the morning between 07:00–10:00 AM, as many hormones follow diurnal variation and peak in the morning (e.g., Cortisol, Testosterone, TSH, GH).

Fasting

Fast for 8–12 hours if the panel includes Insulin, Glucose, or Lipid Profile. Plain water is allowed.

Sleep

Ensure 6–8 hours of sleep. Sleep deprivation significantly affects Cortisol, GH, Prolactin, and TSH levels.

Avoid before test (24–48 hrs)

• Strenuous exercise (affects Cortisol, Testosterone, GH)
• Alcohol (affects Testosterone, Estrogen, Cortisol)
• Severe stress (affects Cortisol, Prolactin)
• Sexual activity (affects Prolactin, Testosterone)

Medications & Supplements

Inform your doctor of all medications. Especially Biotin (Vitamin B7), which interferes with immunoassays — should be discontinued at least 48–72 hours before testing.

Before blood draw

Rest for 15–30 minutes prior to blood collection to reduce hemoconcentration effects.

FSH, LH, Estradiol (E2)

Day 2–5

Early follicular

Reflects true baseline levels

Progesterone

Day 21

Mid-luteal

Confirms ovulation

AMH

Any day

Any phase

Not significantly affected by cycle

Testosterone, DHEA-S

Day 2–5

Follicular phase

Avoid mid-cycle hormonal surge

Prolactin

Day 2–5 (morning)

Morning

Reduces confounding factors

Total Testosterone

Blood should always be drawn before 10:00 AM (levels may decrease by 20–30% in the afternoon). If results are abnormal, repeat testing is recommended for confirmation.

Pre-test Restrictions

• Avoid sexual activity for 24 hours (affects Testosterone, Prolactin)
• Avoid strenuous exercise for 24–48 hours (may cause temporary Testosterone spike followed by a drop)

TRT (Testosterone Replacement Therapy)

If on TRT, timing of blood draw depends on the formulation. For injections, testing is typically done at mid-cycle or trough level, as advised by the physician.

Male Hypogonadism Workup

Total Testosterone, Free Testosterone, SHBG, LH, FSH, Prolactin, and Estradiol can be drawn together in the morning. Fasting is not required unless Insulin/Glucose testing is included.