Testosterone is a hormone that is produced primarily in the testicles in men and in the ovaries in women, with small amounts produced by the adrenal glands.

It is the most important androgen in the body, responsible for the development of male physical characteristics, such as facial hair, low voice, and increased muscle mass. In women, testosterone also plays an important role in muscle strength, bone density, and sexual desire.

Key Functions of Testosterone:

1. Sexual Development : During fetal life, it helps to form male reproductive organs. During adolescence, it stimulates the development of secondary sexual characteristics, such as a low voice and increased body hair.
2. Muscle and Bone Health : Testosterone supports muscle mass and bone density, helping to maintain physical strength and reduce the risk of fractures.
3. Cognitive and Emotional Wellbeing : It influences mood, energy levels, and cognitive functions such as memory and concentration.

Testosterone production is regulated by the hypothalamus and pituitary, which sends signals to the gonads to maintain optimal hormonal balance.

To assess testosterone levels, it is crucial to choose the appropriate tests and to interpret the results based on individual health factors.

Types of Testosterone Tests:

1. Total testosterone : Measures the total amount of testosterone in the blood, including protein-bound testosterone and free testosterone.
2. Free testosterone : Evaluates testosterone that is not bound to proteins, which can be directly used by body tissues.
3. Bioavailable testosterone : Measures free testosterone and that bound to albumin, giving a more accurate view of the quantity accessible to tissues.

Importance of Test Timing:

Testosterone levels peak in the morning (between 7 am and 10 am). It is therefore recommended to schedule the tests at this time for accurate results.

Normal testosterone levels vary by age, gender, and time of day. Here are the general ranges according to Labcorp :

Menu:

• Newborn babies : 75—400 ng/dL.
• 1 to 7 months : 60—400 ng/dL, then stabilization at <10 ng/dL.
• 1 to 10 years : <10 ng/dL.
• Teens (10 to 17 years old) : 100—970 ng/dL (varies according to Tanner's stage).
• Adults (>18 years) : 264—916 ng/dL.

Women:

• Newborn babies : 20—64 ng/dL.
• 1 to 7 months : <10 ng/dL.
• 1 to 9 years : <10 ng/dL.
• Teens (9 to 18 years old) : 7—38 ng/dL (varies according to Tanner's stage).
• Adults : Premenopause: 10—55 ng/dL; Postmenopause: 7—40 ng/dL.

Note: Normal ranges may vary between laboratories and test methods. Consult your doctor to interpret your results.

High testosterone (hyperandrogenism)

Causes:

• Polycystic ovary syndrome (PCOS) : Hormonal disorder common in women.
• Adrenal or Testicular Tumors : Increase testosterone production.
• Steroid Use : May artificially raise testosterone levels.

Symptoms:

• Chez les Hommes : Increased aggressiveness, acne, excessive hair growth and reduced sperm count.
• For women : Male alopecia, hirsutism and irregular menstrual cycles.

Low testosterone (hypogonadism)

Causes:

• Aging : Levels naturally decrease with age.
• Hypogonadism : Insufficiency of the testicles or ovaries to produce testosterone.
• Chronic Diseases : Diabetes, obesity, kidney failure.

Symptoms:

• Chez les Hommes : Low libido, erectile dysfunction, muscle loss, depression.
• For women : Low bone density, fatigue, reduced libido.

Treatments for Low Testosterone:

1. Testosterone Replacement Therapy (TRT) : Administered by injection, patch, gel, or tablets.
2. Lifestyle Changes : A healthy diet, exercise, and quality sleep promote natural testosterone production.
3. Medications : Stimulate testosterone production or treat underlying causes.

Treatments for High Testosterone:

1. Anti-Androgen Drugs : Reduce testosterone levels.
2. Surgery : Removal of tumors in cases where they cause excessive production.
3. Lifestyle Changes : Stress reduction, improved diet, stopping steroids.

If your testosterone levels are abnormal, additional tests may be needed:

• LH and FSH tests : Evaluate hormones that regulate testosterone production.
• Thyroid Function Tests : Thyroid hormones influence testosterone levels.
• Imagery : Detects abnormalities in the adrenal glands or gonads.
• Genetic tests : Diagnostic conditions like Klinefelter syndrome.

These tests help to establish an accurate diagnosis and to plan appropriate treatment.