The evaluation starts with the clinical picture
Laboratory testing is important, but it is only one part of an evaluation. A clinician first considers symptoms, medical history, medications, sleep, fertility goals, and conditions that may affect hormone production or interpretation. Testing is then selected for the individual instead of being ordered as a universal package.
Total testosterone
Total testosterone measures both protein-bound and unbound testosterone in the blood. Because concentrations can change throughout the day, guidelines generally emphasize accurate early-morning testing and confirmation with a second measurement when the first result is low.
One result should not be used by itself to diagnose a testosterone disorder or determine treatment.
Free testosterone and SHBG
Most circulating testosterone is attached to proteins. SHBG, or sex hormone-binding globulin, affects how much testosterone is unbound or “free.” When total testosterone does not clearly match the symptoms, a clinician may assess SHBG and free testosterone using an appropriate method.
SHBG can be influenced by age, body composition, thyroid or liver conditions, metabolic health, and some medicines, which is why interpretation belongs in the broader clinical context.
Tests that may help identify a cause
Depending on the situation, a clinician may consider luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, thyroid testing, a complete blood count, or other studies. LH and FSH can help distinguish a testicular cause from a pituitary or hypothalamic cause. Additional evaluation is not identical for every patient.
Monitoring is different from diagnosis
If treatment is prescribed, follow-up testing may include testosterone concentrations, hematocrit or hemoglobin, blood pressure, and other individualized monitoring. The appropriate schedule depends on the medication, route, health history, response, and current clinical guidance.