A blood test result can sometimes raise questions. The line about testosterone is often one of them. Understanding what this hormone is, its role, and how to interpret its values is a key step in discussing with your doctor and making informed decisions about your health. This article provides you with factual and simple insights into this fundamental biological marker.

What is testosterone?

Testosterone is a steroid hormone derived from cholesterol. It is part of the androgen family. Although people often associate it with masculine characteristics, it is also present and necessary in women, but in smaller quantities. The body primarily produces it in the testicles in men. In women, the ovaries and adrenal glands secrete smaller amounts.

This hormone acts as a chemical messenger that regulates numerous functions. It orchestrates the development of male genitalia and stimulates hair growth. Furthermore, it influences muscle mass and bone density. Testosterone also actively participates in sperm production. In women, it contributes to overall hormonal balance, libido, and maintaining bone health.

Different forms of testosterone in the blood

In the body, testosterone circulates in several forms. A transport protein, SHBG (Sex Hormone-Binding Globulin), firmly binds a large part. Albumin more weakly binds another part. Finally, only a small fraction (1-2%) circulates freely. This free form is directly active on cells. A blood test can measure total testosterone (all these forms) or its bioavailable fraction (free + albumin-bound), which better reflects its actual activity.

Why is monitoring testosterone important?

Testosterone has an impact far beyond simple reproductive function. It influences metabolism, cardiovascular health, and even cognitive functions. An imbalance of this marker can therefore have significant consequences on overall health.

In men, a prolonged testosterone deficiency can contribute to osteoporosis, decreased muscle mass, weight gain, chronic fatigue, or mood disorders. Conversely, a very high level can sometimes signal a testicular or adrenal pathology.

In women, doctors often link excess testosterone to conditions such as polycystic ovary syndrome (PCOS). If left untreated, this imbalance can lead to metabolic disorders or infertility. Therefore, testosterone measurement is an important diagnostic tool that helps doctors guide treatments.

How to read and interpret your testosterone tests?

Your test report generally presents your measured value next to the laboratory’s reference values. These are established for a given sex and age range.

The most common units are nanograms per milliliter (ng/mL) and nanomoles per liter (nmol/L). It is crucial to check the unit used for correct interpretation.

Here are typical reference ranges for total testosterone:

• In adult men: between 2.8 and 8.0 ng/mL (or approximately 9.7 to 27.8 nmol/L)
• In adult women: between 0.15 and 0.7 ng/mL (or approximately 0.5 to 2.4 nmol/L)

Note that these values vary slightly from one laboratory to another. Furthermore, testosterone levels naturally rise in the morning. This is why doctors often recommend having the blood drawn between 7 AM and 10 AM.

What conditions are linked to a testosterone imbalance?

Various medical conditions can be associated with abnormal levels of this hormone.

Conditions associated with low testosterone levels

Doctors link male hypogonadism to testosterone deficiency. They define this condition as insufficient testosterone production by the testicles. Doctors observe symptoms that include fatigue, decreased libido, loss of muscle mass, or mood disorders. The diagnosis may require additional measurements (LH, FSH) or imaging.

With age, testosterone production also naturally decreases in men. Doctors call this phenomenon age-related androgen deficiency (ARAD). Finally, metabolic syndrome, particularly abdominal obesity, often lowers testosterone levels.

Conditions associated with high testosterone levels

In women, the most common cause of excess testosterone is polycystic ovary syndrome (PCOS). It manifests as irregular menstrual cycles, acne, or excessive hairiness (hirsutism).

More rarely, a very high level can signal a tumor of the ovaries or adrenal glands, in both women and men. Another possible cause is congenital adrenal hyperplasia, a genetic disease. These situations require in-depth medical investigations.

Practical tips for managing your testosterone levels

Good lifestyle habits are fundamental to maintaining optimal hormonal balance.

Follow-up schedule

• For a normal level: In men over 50, an annual check-up can be discussed with the doctor. For others, follow-up is only indicated in case of symptoms.
• For a slightly abnormal level: A new check-up after a few months is often proposed to confirm the variation.
• For a very abnormal level: Follow-up will be defined by your specialist doctor based on the cause and the treatment implemented.

Optimization through nutrition and lifestyle

Balanced Diet

To promote adequate testosterone levels, a nutrient-rich diet is essential. Prioritize foods containing zinc (lean meat, pumpkin seeds) and vitamin D (fatty fish, eggs). Good fats, found in avocado or olive oil, are also important. Conversely, excessive consumption of alcohol and refined sugars can be harmful.

Physical activity and sleep

Regular resistance exercise (strength training) is beneficial. Quality sleep, about 7 to 8 hours per night, is also crucial for hormonal regulation. Stress management is another pillar, as high levels of cortisol (the stress hormone) can negatively affect testosterone production.

Environment and endocrine disruptors

Scientists and health authorities recommend reducing exposure to endocrine disruptors. These chemicals are found in certain plastics or pesticides. Preferably use glass or stainless steel containers for food.

Frequently Asked Questions about Testosterone

Are there drug interactions with testosterone testing?

Yes, certain medications can influence the results. Treatments with corticosteroids, some antiepileptics, or opioids can alter testosterone levels. It is therefore essential to inform your doctor of all your current treatments before an analysis.

What is the difference between total and bioavailable testosterone?

Total testosterone measures all the hormone in the blood (protein-bound and free). Bioavailable testosterone measures the active fraction, meaning the free form and the form weakly bound to albumin. This second measurement is sometimes more relevant in certain clinical situations such as obesity.

Does prolonged fasting affect testosterone levels?

Yes, fasting for more than 24 hours can lead to a significant drop in testosterone levels. The body implements survival mechanisms that reduce hormone production. It is therefore recommended not to have been fasting for a long time before a measurement.

In conclusion: a marker to know

Testosterone is a central biological marker for the health of men and women. Understanding its role allows for better interpretation of a blood analysis and active participation in medical follow-up. Variations in this marker are not uncommon and can signal various conditions. Often, lifestyle adjustments are enough to maintain a good balance. In all cases, a discussion with your doctor is the best approach to evaluate your personal situation.

Additional resources

• To deepen your knowledge of this blood marker, click here.
• To extend your knowledge and decipher other markers, more articles are available here.

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