Diagnostic Blood Test: Total Testosterone, Standard (ECLIA) Testosterone is the primary sex hormone in men and plays important roles in women. Low testosterone levels may play a role in erectile dysfunction, decreased sex drive, muscle loss, weak bones, hair loss, fatigue, depression, memory problems, heart disease, and even earlier death. Optimal testosterone levels may lead to increased muscle mass and strength, higher endurance, enhanced libido, improved mood, lower cholesterol levels, increased bone mineral density, improved cognition and memory, better sleep, and a healthier metabolism. Total Testosterone is a measure of the total amount of testosterone hormone in the blood.Note: This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin. Cease biotin supplementation at least 72 hours prior to blood draw.