Laboratory Medicine
Test Directory / Free Androgen Index
Free Androgen Index
Brown clotted serum, gel barrier
| Test | Free Androgen Index |
|---|---|
| Common Abbreviations | FAI |
| Profile | Consists of testosterone and SHBG |
| Tube type | Brown clotted serum, gel barrier |
| Clinical Indication | Sex hormone binding protein (SHBG) levels are commonly measured as a supplement to total testosterone because variations in the carrier protein may affect the concentration of testosterone in circulation. The Free Androgen Index (FAI) is calculated as the ratio of total testosterone to SHBG and has proved a useful indicator of abnormal androgen status in conditions such as polycycstic ovary syndrome and hirsutism. This is particularly useful when the total testosterone concentration is normal but the SHBG is low, resulting in an elevated concentration of non-protein bound testosterone. FAI is only reported in female patients. |
| Specimen Type | Blood |
| Sample type | Serum |
| Minimum Volume | 0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample. |
| Special Precautions | No special requirements |
| Stability | See Testosterone and Sex Hormone Binding Protein |
| Turnaround Time | Inpatient: 48 hours Outpatient/ GP: 48 hours |
| Laboratory | York |
| Reference Interval | Females only: 20 - 49 years: 0.3 - 5.6% > 50 years: 0.2 - 3.6% |
| Limitations | See Testosterone and Sex Hormone Binding Protein |
| Notes |
