Testosterone, Free
CPT Code(s):
84403, 84402, 84270
Turnaround Time:
8 hours
Specimen Requirements
Preferred Specimen:
Serum
Minimum Volume:
1.0 mL
Transport Container:
Serum Separator Tube (SST) or Red Top Tube
Transport Temperature:
Room Temperature
Collection Instructions:
Allow blood to clot completely prior to centrifugation. Separate serum from cells within 45 minutes of collection.
Rejection Criteria:
Sodium Citrate plasma; gross hemolysis; lipemia; improper labeling
Stability Criteria
Room Temperature:
48 hours
Refrigerated:
7 days
Frozen:
30 days
Clinical Significance
The Testosterone, Free and Total with SHBG is a comprehensive diagnostic tool used to assess the levels of both free and total testosterone, as well as sex hormone-binding globulin (SHBG), in a patient's blood. This test has specific clinical significance and diagnostic use in the following ways:
1. Evaluation of Hypogonadism: Hypogonadism is a condition characterized by low testosterone levels, which can lead to symptoms such as reduced libido, fatigue, muscle weakness, and mood changes. The measurement of both free and total testosterone, along with SHBG levels, helps in diagnosing and monitoring hypogonadism. It provides a comprehensive assessment of testosterone status and aids in differentiating between primary and secondary causes of the condition.
2. Assessment of Androgen-Related Disorders: Disorders related to androgen deficiency or excess, such as polycystic ovary syndrome (PCOS) in women or androgen insensitivity syndrome (AIS) in men, can be evaluated through the measurement of free and total testosterone with SHBG. This test helps in determining the balance between bound and unbound testosterone and assists in diagnosing and managing these disorders.
3. Monitoring Testosterone Replacement Therapy: Testosterone replacement therapy (TRT) is often prescribed to individuals with low testosterone levels. Measuring both free and total testosterone, along with SHBG levels, aids in monitoring the effectiveness of TRT and ensuring that therapeutic levels are achieved and maintained. This information enables healthcare providers to optimize TRT dosages and treatment regimens.
4. Assessing Hormonal Imbalances: Hormonal imbalances can occur due to various factors, such as obesity, thyroid disorders, or liver dysfunction. Measuring both free and total testosterone, along with SHBG levels, contributes to a comprehensive evaluation of hormonal status. It helps in identifying imbalances and guiding appropriate treatment strategies.
5. Determining Free Androgen Index (FAI): Free Androgen Index is a calculated value obtained by dividing the totalosterone level by SHBG level and multiplying by 100. It provides an estimate of the biologically active fraction of testosterone in the bloodstream. The FAI can be useful in assessing androgen status in certain clinical situations.
It is important to note that the interpretation of test results should be done in conjunction with the patient's clinical presentation, medical history, and other laboratory findings. Reference ranges may vary depending on the laboratory performing the test, and assay methods for testosterone and SHBG measurement can differ.
In summary, the Testosterone, Free and Total with SHBG is clinically significant and diagnostically useful for evaluating hypogonadism, assessing androgen-related disorders, monitoring testosterone replacement therapy, assessing hormonal imbalances, and determining the Free Androgen Index. It provides valuable information for healthcare providers in diagnosing and managing patients with testosterone-related conditions, optimizing treatment regimens, and guiding patient care.