Fasting Testosterone Test Protocol and Treatment of Low Testosterone
The diagnosis of testosterone deficiency requires two fasting morning total testosterone measurements below 300 ng/dL, along with the presence of symptoms such as reduced energy, fatigue, depression, poor concentration, and reduced sex drive. 1
Proper Testing Protocol
- Testosterone should be measured in the early morning (between 8-10 AM) due to diurnal variation in testosterone production 1, 2
- Patients should be in a fasting state for accurate measurement 2, 3
- Two separate morning measurements are required to confirm diagnosis 1, 3
- Measurements should ideally be performed using liquid chromatography-tandem mass spectrometry in a laboratory certified by an accuracy-based program 2
- Both samples should show testosterone levels consistently below 300 ng/dL to diagnose testosterone deficiency 1
- Samples should be taken using the same laboratory with the same method/instrumentation for measurement 1
Additional Testing
- Serum luteinizing hormone (LH) levels should be measured to establish the etiology of testosterone deficiency 1, 4
- Serum prolactin levels should be measured in patients with low testosterone combined with low or low/normal LH levels 1, 4
- Consider pituitary MRI if total testosterone is <150 ng/dL with low/normal LH levels, as non-secreting adenomas may be present 1, 4
- Measure serum estradiol in patients who present with breast symptoms or gynecomastia prior to starting testosterone therapy 1, 4
Treatment Approach for Low Testosterone
- Testosterone replacement therapy is the recommended first-line treatment for patients with confirmed low testosterone and symptoms 4, 5
- Target testosterone levels should be in the mid-normal range during treatment 4, 5
- Choice of formulation (transdermal or intramuscular) should consider pharmacokinetics, treatment burden, and cost 4, 5
- For patients wishing to preserve fertility, consider gonadotropin therapy or selective estrogen receptor modulators instead of testosterone therapy 4
Testosterone Therapy Options
- Transdermal formulations (gels): Apply to shoulders and upper arms at the same time each morning after showering 5
- Intramuscular injections: Dosing varies based on formulation 1
- Dosing should be titrated to achieve testosterone levels in the mid-normal range 4, 5
Monitoring During Treatment
- Monitor testosterone levels to ensure they remain in the target range 5
- Monitor hemoglobin/hematocrit, as testosterone therapy can increase these values 6
- Monitor PSA in men older than 40 years 6
- Monitor for potential side effects, including changes in estradiol levels and possible breast symptoms 6
Lifestyle Modifications
- Weight loss through low-calorie diets can improve testosterone levels in obese patients with secondary hypogonadism 4
- Regular physical activity shows similar benefits, though testosterone increases are typically modest 4
- Consider combining lifestyle modifications with testosterone therapy for better outcomes in symptomatic patients 4
Common Pitfalls and Considerations
- Single testosterone measurements are insufficient for diagnosis; confirmation with repeat testing is essential 1, 7
- Free testosterone levels should be measured in men with suspected alterations in binding protein concentrations or when total testosterone levels are borderline 2, 3
- Testosterone therapy is contraindicated in men with breast cancer, prostate cancer, or those trying to conceive 5
- Secondary exposure to testosterone can occur with gel formulations; patients must be counseled on proper application and precautions 5
- Testosterone therapy is not recommended for men with low testosterone due to aging alone without symptoms 5