What are the symptoms of low FAI?
Low Free Androgen Index (FAI) can cause fatigue, reduced libido, muscle weakness, mood changes, and metabolic issues in both men and women. Testing your hormones through comprehensive panels can help identify FAI imbalances and guide treatment.
Jump To Section
Understanding Free Androgen Index (FAI)
The Free Androgen Index (FAI) is a calculated ratio that estimates the amount of biologically active testosterone circulating in your bloodstream. Unlike total testosterone measurements, FAI provides insight into how much testosterone is actually available for your body to use, making it a more accurate indicator of androgen status.
FAI is calculated by dividing total testosterone by sex hormone-binding globulin (SHBG) and multiplying by 100. SHBG is a protein that binds to testosterone and other sex hormones, essentially "locking them up" and preventing them from being used by your tissues. When SHBG levels are high or testosterone levels are low, your FAI decreases, potentially leading to symptoms of androgen deficiency.
While low FAI is often associated with men's health issues, it's equally important for women. Both sexes require adequate levels of free androgens for optimal health, though the normal ranges differ significantly. Understanding your FAI can help identify hormonal imbalances that might be affecting your energy, mood, body composition, and overall wellbeing.
Common Causes of Low FAI by Category
| Category | Specific Causes | Mechanism | Reversibility | |
|---|---|---|---|---|
| Hormonal | Hormonal | Hypogonadism, Aging | Decreased testosterone production | Partially reversible with treatment |
| Metabolic | Metabolic | Obesity, Diabetes, Metabolic syndrome | Increased aromatase, insulin resistance | Often reversible with lifestyle changes |
| Medications | Medications | Opioids, Steroids, Antidepressants | Suppression of hormone production | Usually reversible upon discontinuation |
| Lifestyle | Lifestyle | Poor sleep, Chronic stress, Alcohol | Cortisol elevation, hormone disruption | Highly reversible with changes |
| Medical | Medical | Liver disease, Thyroid disorders | Increased SHBG production | Depends on underlying condition |
Understanding the cause of low FAI is crucial for determining the most effective treatment approach.
Common Symptoms of Low FAI in Men
Men with low FAI often experience a constellation of symptoms that can significantly impact quality of life. These symptoms typically develop gradually and may be mistaken for normal aging or stress-related issues.
Physical Symptoms
- Persistent fatigue and low energy levels, even with adequate sleep
- Decreased muscle mass and strength despite regular exercise
- Increased body fat, particularly around the midsection
- Reduced bone density, increasing fracture risk
- Hot flashes and night sweats
- Decreased body and facial hair growth
- Gynecomastia (enlarged breast tissue)
Sexual and Reproductive Symptoms
- Reduced libido or complete loss of sex drive
- Erectile dysfunction or difficulty maintaining erections
- Decreased morning erections
- Reduced semen volume
- Infertility or subfertility issues
- Testicular atrophy (shrinking of the testicles)
Psychological and Cognitive Symptoms
- Depression, anxiety, or mood swings
- Irritability and decreased stress tolerance
- Poor concentration and memory problems
- Reduced motivation and drive
- Sleep disturbances, including insomnia
- Decreased self-confidence
Common Symptoms of Low FAI in Women
While women naturally have lower androgen levels than men, maintaining adequate FAI is crucial for female health. Low FAI in women can manifest through various symptoms that are often overlooked or attributed to other conditions.
Physical and Metabolic Symptoms
- Chronic fatigue and weakness
- Loss of muscle tone and strength
- Weight gain, especially abdominal fat
- Thinning hair or hair loss
- Dry skin and brittle nails
- Joint pain and stiffness
- Decreased bone density
Sexual and Reproductive Symptoms
- Significantly reduced libido
- Vaginal dryness and discomfort
- Difficulty achieving orgasm
- Irregular menstrual cycles
- Fertility challenges
- Decreased sexual satisfaction
Emotional and Cognitive Symptoms
- Depression and anxiety
- Brain fog and difficulty concentrating
- Memory problems
- Mood swings and irritability
- Decreased motivation and assertiveness
- Poor stress resilience
Causes of Low FAI
Understanding what causes low FAI is essential for proper treatment. The condition can result from either decreased testosterone production, increased SHBG levels, or a combination of both.
Primary Causes
- Aging: Natural decline in testosterone production
- Hypogonadism: Primary (testicular/ovarian) or secondary (pituitary/hypothalamic)
- Chronic illnesses: Diabetes, liver disease, kidney disease, HIV/AIDS
- Medications: Opioids, corticosteroids, certain antidepressants
- Obesity and metabolic syndrome
- Chronic stress and elevated cortisol
- Sleep disorders, particularly sleep apnea
Factors That Increase SHBG
- Hyperthyroidism or elevated thyroid hormones
- Liver disease or cirrhosis
- Oral contraceptives or hormone replacement therapy
- Certain medications like anticonvulsants
- Aging in men
- Anorexia or severe caloric restriction
- Excessive alcohol consumption
Upload your blood test results to track your progress
Seamlessly upload 3rd party biomarker & blood tests to track your whole health in 1 dashboard. Understand what each blood test means and how it fits into the bigger picture of your body and health.
Get diet and lifestyle recommendations based on your blood results, health profile and health goals. You'll also receive a custom supplement recommendation for the precise nutrients your body craves.
Upload Past Blood Test Results
Click or drag file to upload
Once you upload your report, we'll extract the results for your review. Works with top labs including Quest Diagnostics, LabCorp, BioReference, EverlyWell, LetsGetChecked and hundreds of other labs.
Diagnosing Low FAI
Accurate diagnosis of low FAI requires comprehensive hormone testing that goes beyond simple total testosterone measurements. A complete evaluation should include total testosterone, SHBG, and albumin levels to calculate both FAI and free testosterone.
The normal FAI ranges vary significantly between men and women. For men, a normal FAI typically ranges from 30-150, while for women, the range is much lower at 0.5-10. However, these ranges can vary based on the laboratory and testing methodology used.
Additional tests that may be helpful in evaluating low FAI include luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol, DHEA-S, and thyroid function tests. These markers can help identify the underlying cause of hormonal imbalances and guide appropriate treatment strategies.
Treatment Options for Low FAI
Treatment for low FAI depends on the underlying cause and individual circumstances. The goal is to restore hormonal balance while addressing any contributing factors.
Lifestyle Modifications
- Weight loss through diet and exercise to reduce aromatase activity
- Resistance training to naturally boost testosterone production
- Stress management techniques like meditation or yoga
- Improving sleep quality and duration (7-9 hours nightly)
- Limiting alcohol consumption
- Optimizing vitamin D and zinc levels through diet or supplementation
Medical Treatments
- Testosterone replacement therapy (TRT) for men with confirmed hypogonadism
- Androgen therapy for women (lower doses than men)
- Medications to lower SHBG if elevated
- Treatment of underlying conditions (thyroid disorders, diabetes)
- Adjustment of medications that may be suppressing testosterone
- Clomiphene citrate or hCG for men wanting to preserve fertility
Long-term Health Implications
Untreated low FAI can have serious long-term health consequences beyond the immediate symptoms. Research has shown associations between low FAI and increased risk of cardiovascular disease, type 2 diabetes, osteoporosis, and metabolic syndrome.
In men, chronic low FAI has been linked to increased mortality risk, particularly from cardiovascular causes. Women with low FAI may experience accelerated bone loss after menopause and increased risk of fractures. Both sexes may experience cognitive decline and increased risk of dementia with prolonged androgen deficiency.
Regular monitoring of FAI and related hormones is essential for maintaining optimal health throughout life. Early detection and treatment of hormonal imbalances can prevent many of these long-term complications and significantly improve quality of life.
Taking Action: Next Steps for Low FAI
If you're experiencing symptoms of low FAI, the first step is comprehensive hormone testing. This should include not just total testosterone but also SHBG, albumin, and other relevant hormones to get a complete picture of your hormonal health.
Work with a healthcare provider who understands hormone optimization and can interpret your results in the context of your symptoms and health goals. Treatment should be individualized based on your specific situation, taking into account factors like age, fertility desires, and overall health status.
Remember that hormone optimization is a journey, not a destination. Regular monitoring and adjustment of treatment strategies ensure the best outcomes while minimizing potential risks. With proper diagnosis and treatment, most people with low FAI can experience significant improvement in their symptoms and overall quality of life.
References
- Travison, T. G., Araujo, A. B., O'Donnell, A. B., Kupelian, V., & McKinlay, J. B. (2007). A population-level decline in serum testosterone levels in American men. The Journal of Clinical Endocrinology & Metabolism, 92(1), 196-202.[PubMed][DOI]
- Davis, S. R., Wahlin-Jacobsen, S. (2015). Testosterone in women—the clinical significance. The Lancet Diabetes & Endocrinology, 3(12), 980-992.[PubMed][DOI]
- Vermeulen, A., Kaufman, J. M., & Giagulli, V. A. (1996). Influence of some biological indexes on sex hormone-binding globulin and androgen levels in aging or obese males. The Journal of Clinical Endocrinology & Metabolism, 81(5), 1821-1826.[PubMed][DOI]
- Bhasin, S., Brito, J. P., Cunningham, G. R., Hayes, F. J., Hodis, H. N., Matsumoto, A. M., ... & Yialamas, M. A. (2018). Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. The Journal of Clinical Endocrinology & Metabolism, 103(5), 1715-1744.[PubMed][DOI]
- Rosner, W., Auchus, R. J., Azziz, R., Sluss, P. M., & Raff, H. (2007). Position statement: Utility, limitations, and pitfalls in measuring testosterone: an Endocrine Society position statement. The Journal of Clinical Endocrinology & Metabolism, 92(2), 405-413.[PubMed][DOI]
- Glaser, R., & Dimitrakakis, C. (2013). Testosterone therapy in women: Myths and misconceptions. Maturitas, 74(3), 230-234.[PubMed][DOI]
Was this article helpful?
Frequently Asked Questions
How can I test my FAI at home?
What is the normal FAI range for men and women?
Can low FAI be reversed naturally?
How long does it take to see improvements in FAI levels?
What's the difference between FAI and free testosterone?
This article is licensed under CC BY 4.0. You are free to share and adapt this material with attribution.
