游离睾酮（计算）

Testosterone, Free (Calculation) 

The Testosterone, Free (Calculation) test estimates the level of free testosterone in the blood by using total testosterone, sex hormone-binding globulin (SHBG), and sometimes albumin. Free testosterone represents the bioavailable hormone not bound to SHBG and is critical for assessing androgen status, especially in men. 

1. What Is Free Testosterone? 
• Testosterone in the blood exists in three forms: bound to SHBG, loosely bound to albumin, and free (unbound). 
• Free testosterone is the active form that can interact with receptors in the body’s tissues. 
• This test uses a mathematical formula to estimate free testosterone from total testosterone and SHBG levels. 

2. Why Is the Test Performed? 
• To assess testosterone status in men with symptoms of low testosterone (e.g., fatigue, low libido, erectile dysfunction). 
• To evaluate androgen levels in women with symptoms of excess testosterone (e.g., hirsutism, irregular periods). 
• To differentiate between types of low testosterone (e.g., due to SHBG abnormalities vs. true hypogonadism). 

3. Interpreting Results 
🔹 Low Free Testosterone: 
• May indicate hypogonadism or decreased androgen activity. 
• May occur even when total testosterone appears normal, especially with high SHBG. 

🔹 High Free Testosterone: 
• May be associated with polycystic ovary syndrome (PCOS), adrenal disorders, or anabolic steroid use. 

4. What Can Affect Free Testosterone Levels? 
• SHBG levels (affected by age, liver disease, obesity, thyroid function). 
• Medications (e.g., corticosteroids, antiandrogens, hormone therapy). 
• Chronic illness or stress. 

5. How Is the Test Performed? 
• A blood sample is taken, and free testosterone is calculated using total testosterone and SHBG results. 

6. When to See a Doctor 
🚨 Contact your healthcare provider if you: 
• Experience symptoms of low or high testosterone. 
• Have abnormal total testosterone levels or symptoms not explained by those levels. 
• Are undergoing hormone replacement or fertility evaluation. 

🔹 Key Takeaways 
✅ Free testosterone provides insight into the biologically active hormone in the body. 
✅ It is especially useful when SHBG levels may alter total testosterone interpretation. 
✅ This calculation supports diagnosis and treatment of hormonal imbalances in men and women.