Testosterone is a naturally occurring hormone present in both men and women, playing many roles throughout the body. While primarily associated with male characteristics, it contributes to overall health in both sexes, influencing everything from bone density and muscle mass to mood and sexual function. Understanding the typical levels of this hormone is important for assessing health.
Understanding a Reference Range
A “reference range” in medical testing represents the expected values for a particular measurement in a healthy population. These ranges are established by collecting data from a large number of healthy individuals, statistically determining the upper and lower limits that encompass the majority of those results. A small percentage of healthy individuals may still have results outside this range.
A reference range acts as a guide rather than an absolute threshold for health. These ranges can vary slightly between different laboratories due to differences in testing methods or populations. Therefore, a result should always be interpreted using the reference range provided by the laboratory that performed the test.
Typical Testosterone Levels
Testosterone levels naturally fluctuate throughout a person’s life and vary significantly between sexes. For adult males, typical total testosterone levels generally fall between 265 and 923 nanograms per deciliter (ng/dL). Free testosterone levels, which represent the unbound and biologically active form of the hormone, also have specific ranges that vary with age.
Testosterone levels in males are highest during adolescence and early adulthood, peaking in their 20s. After age 30, total testosterone levels in men may gradually decline by approximately 1% to 2% per year.
Adult females have considerably lower testosterone levels compared to males, generally ranging from 15 to 70 ng/dL. In premenopausal women, levels are between 10 to 55 ng/dL, while postmenopausal women may have levels between 7 to 40 ng/dL. Testosterone levels in females also decline with age, with a more noticeable reduction occurring after menopause.
Recognizing Imbalances
When testosterone levels fall below the typical reference range, a condition often referred to as low testosterone or hypogonadism, several symptoms can emerge. In men, these may include:
- Reduced sex drive
- Difficulty achieving or maintaining erections
- Fatigue
- Reduced muscle mass and strength
- Increased body fat
- Decreased bone density
- Mood changes such as irritability, depression, and difficulty concentrating
Conversely, elevated testosterone levels can also lead to noticeable symptoms, particularly in women. These may manifest as:
- Excessive body hair growth (hirsutism)
- Acne and oily skin
- Irregular menstrual cycles or absence of periods (amenorrhea)
- Deepening of the voice
- Increased muscle mass
- Potential infertility
While less obvious in men, high testosterone can lead to issues such as:
- Acne
- Headaches
- High blood pressure
- Prostate enlargement
Testing and Interpretation
Measuring testosterone levels involves a blood test, and the timing of sample collection is important for accurate results. Testosterone levels exhibit a circadian rhythm, meaning they fluctuate throughout the day, peaking in the early morning. For this reason, blood samples are usually collected between 7 AM and 11 AM, sometimes in a fasting state, to capture the highest and most stable levels.
Several factors beyond natural daily variations can influence testosterone test results. Age is a factor, as levels naturally decline over time. Other influences include certain medications, such as opioids or steroids, acute illnesses, and lifestyle factors like sleep quality and body weight. Due to these variables, if initial results are unusually high or low, a healthcare provider may recommend a second test to confirm the findings. Interpreting test results should always be done in conjunction with a person’s symptoms and overall health history, and a healthcare professional should be consulted for diagnosis and intervention.