Why Lab Interpretation Is the Most Critical Skill in Hormone Medicine
Any practitioner can order a hormone panel. The real clinical skill is knowing how to interpret results in context — understanding what the numbers mean relative to patient symptoms, age, lifestyle, and treatment goals. This guide walks through the key markers on a standard hormone panel and how to think about them clinically.
Total Testosterone vs. Free Testosterone
Total testosterone measures all testosterone in the bloodstream, including protein-bound forms. Free testosterone represents the biologically active fraction. A patient can have a “normal” total testosterone (e.g., 450 ng/dL) but low free testosterone if SHBG is elevated — and still present with hypogonadal symptoms. Always evaluate both numbers together.
SHBG: The Binding Variable
Sex hormone-binding globulin (SHBG) binds testosterone (and estrogen) tightly, rendering it unavailable to tissues. High SHBG is common in older men, men with hyperthyroidism, and those with high alcohol intake or liver issues. Low SHBG is associated with insulin resistance and obesity. Elevated SHBG requires higher testosterone levels to achieve adequate free testosterone.
LH and FSH: Reading the Feedback Loop
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) tell you where the problem originates. Low testosterone with low/normal LH and FSH = secondary (central) hypogonadism. Low testosterone with high LH and FSH = primary hypogonadism (testicular failure). This distinction has treatment and prognostic implications.
Estradiol in Men and Women
In men, an optimal estradiol range is typically 20–40 pg/mL. Too low causes bone loss, poor libido, and mood dysregulation. Too high causes water retention, gynecomastia, and cardiovascular risk. In women, estradiol interpretation depends heavily on menopausal status and where they are in their cycle.
Thyroid Markers: Don’t Stop at TSH
Many practitioners only run TSH — a significant oversight. Patients can have a “normal” TSH but elevated reverse T3, depressed free T3, or positive thyroid antibodies indicating Hashimoto’s. A full thyroid panel includes: TSH, free T4, free T3, reverse T3, TPO antibodies, and thyroglobulin antibodies.
Cortisol and DHEA
Chronic stress dysregulates the HPA axis, affecting cortisol patterns and DHEA production. A morning serum cortisol or 4-point salivary cortisol test can reveal adrenal dysfunction patterns that explain fatigue, poor recovery, and hormonal imbalance. DHEA-S is a useful proxy for adrenal reserve and declines significantly with age.
Clinical Takeaway
Always interpret labs in the context of symptoms. A patient with a testosterone of 310 ng/dL and severe hypogonadal symptoms deserves treatment consideration. A patient with 290 ng/dL and no symptoms may not. The lab is a tool — not the diagnosis.