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What is free testosterone?

Free testosterone is the fraction of testosterone in the blood that is not bound to proteins such as SHBG and albumin. This bioactive form of testosterone plays a crucial role in many physiological processes, including sexual health, muscle mass, bone density, and mood regulation. Unlike total testosterone, free testosterone is the portion that is readily available to the body’s tissues to exert its effects.

In males, testosterone is primarily produced by the testes, under the regulation of the pituitary gland. Although only 1–2% of the testosterone in a man’s body is free, it is essential for driving bodily functions. Free testosterone levels naturally decline as men age, but maintaining balanced testosterone is crucial for overall health and vitality. In females, testosterone is primarily produced by the ovaries and adrenal glands. Even small fluctuations in free testosterone can have a significant impact on health, including symptoms such as low libido, fatigue, and muscle weakness.

Why is free testosterone important?

Free testosterone is essential for:

  • Males: sexual health, sperm production, muscle growth, bone density, mood, and vitality.
  • Females: libido, lean muscle maintenance, energy, emotional stability, and bone strength.

Low free testosterone in either sex can lead to fatigue, reduced muscle mass, low libido, and mood imbalances even if total testosterone appears normal.

High free testosterone can also signal problems:

  • In men: is often seen in exogenous steroid users and can cause acne, aggression, or hair loss.
  • In women: may indicate conditions like PCOS, and cause hirsutism, acne, or irregular periods.

How can I better understand my free testosterone levels?

Free testosterone is typically tested alongside total testosterone to assess hormonal activity. Levels vary by:

  • Age (typically decreasing over time)
  • Time of day (highest in the early morning due to diurnal rhythm)
  • Sex, menstrual cycle (in females), and menopausal status

Lab Ranges:

Male:

  • Out of range (low): <0.03 ng/mL
  • In range: 0.03-0.2 ng/mL
  • Out of range (high): >0.2 ng/mL

Female:

  • Out of range (low): <1.1 pg/mL
  • In range: 1.1-12.9 pg/mL
  • Out of range (high): >12.9 pg/mL

SiPhox Ranges:

Male:

Age Optimal Range Good Range Fair Range
20-39 yrs 0.13-0.30 ng/mL 0.08-0.30 ng/mL >0.05 ng/mL
40-49 yrs 0.1-0.29 ng/mL 0.06-0.29 ng/mL >0.04 ng/mL
50-59 yrs 0.1-0.28 ng/mL 0.06-0.28 ng/mL >0.04 ng/mL
60-69 yrs 0.09-0.27 ng/mL 0.05-0.27 ng/mL >0.03 ng/mL
>70 yrs 0.08-0.26 ng/mL 0.04-0.26 ng/mL >0.03 ng/mL

Female:

  • Good Range: 1.1-12.9 pg/mL

How can I maintain optimal free testosterone levels?

Dietary Changes:  A diet rich in lean proteins, healthy fats, antioxidant-rich foods, and hormone-supporting herbs like ginger and turmeric can support testosterone regulation. Including honey can help to increase lower testosterone levels. Research suggests that macronutrient, vitamin, and mineral intake can impact testosterone synthesis. Spearmint tea may reduce excess testosterone, especially in women with conditions like PCOS. Zinc-containing foods like oysters and pumpkin seeds can also regulate testosterone.

Lifestyle Changes: Avoiding chronic stressors, getting more and higher-quality sleep, and lowering abdominal fat percentage through a healthy regimen can help in improving testosterone levels. Additionally, engaging in regular physical activity, including strength training and aerobic exercise, can help support hormone balance, muscle strength, and overall well-being. Practicing stress-reducing techniques such as mindfulness, meditation, deep breathing exercises, and adequate sleep can also help support hormone balance and overall health.

Supplementation: Supplements like fenugreek seed extract, ashwagandha roots and leaves, and  saw palmetto or boron can help to increase lower free testosterone levels. Adequate zinc intake has also been shown to regulate both elevated and decreased hormone levels, including testosterone. These supplements are not recommended in pregnancy or for individuals with kidney disease.

Where can I learn more?

DISCLAIMER: IF YOU ARE CONCERNED WITH ANY OF YOUR RESULTS, PLEASE CONSULT WITH YOUR PHYSICIAN.