From the Guidelines
When evaluating testosterone levels in males, order total testosterone as the initial screening test, ideally drawn in the morning when levels are highest, and consider additional tests such as sex hormone binding globulin (SHBG), free or bioavailable testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) to determine the underlying cause of hypogonadism 1.
Initial Evaluation
The initial evaluation of testosterone levels in males should include a morning total testosterone level measurement using an accurate and reliable assay 1. This is because testosterone levels are typically highest in the morning, and measuring at this time provides a more accurate representation of the patient's testosterone status.
Additional Tests
If the total testosterone level is low or borderline, additional tests such as SHBG and free or bioavailable testosterone may be necessary to assess the active hormone fraction 1. LH and FSH levels can also help determine if hypogonadism is primary (testicular) or secondary (pituitary/hypothalamic) 1.
Considerations
Other hormones that can affect testosterone production, such as prolactin, estradiol, and thyroid function tests (TSH, free T4), should also be considered 1. A complete blood count (CBC) and comprehensive metabolic panel (CMP) can provide baseline health information, while hematocrit monitoring may be necessary if polycythemia is present or testosterone therapy is planned 1. For men with fertility concerns, a semen analysis may also be indicated.
Comprehensive Evaluation
These tests should be interpreted together for a comprehensive evaluation of male hormonal health, as testosterone levels can be affected by various factors including time of day, stress, medications, obesity, and chronic illness 1. The diagnosis of testosterone deficiency requires both a low testosterone measurement and the presence of select symptoms and/or signs, and clinicians should use a total testosterone level below 300 ng/dL as a reasonable cut-off in support of the diagnosis of low testosterone 1.
From the FDA Drug Label
Prior to initiating testosterone gel 1. 62%, confirm the diagnosis of hypogonadism by ensuring that serum testosterone has been measured in the morning on at least two separate days and that these concentrations are below the normal range Dose adjustment: testosterone gel 1.62% can be dose adjusted between a minimum of 20.25 mg of testosterone (1 pump actuation or a single 20. 25 mg packet) and a maximum of 81 mg of testosterone (4 pump actuations or two 40.5 mg packets). The dose should be titrated based on the pre-dose morning serum testosterone concentration at approximately 14 days and 28 days after starting treatment or following dose adjustment. Additionally, serum testosterone concentration should be assessed periodically thereafter. Monitor serum testosterone, prostate specific antigen (PSA), hemoglobin, hematocrit, liver function tests and lipid concentrations periodically.
The laboratory tests indicated when evaluating testosterone levels in males are:
- Serum testosterone
- Prostate specific antigen (PSA)
- Hemoglobin
- Hematocrit
- Liver function tests
- Lipid concentrations 2
From the Research
Laboratory Tests for Evaluating Testosterone Levels in Males
The following laboratory tests are indicated when evaluating testosterone levels in males:
- Total testosterone (TT) level, which should be measured in a fasting state in the morning using a reliable assay, such as liquid chromatography tandem mass spectrometry 3
- Free testosterone (FT) level, which should be measured in men in whom alterations in binding protein concentrations are suspected or in whom total testosterone levels are only slightly above or slightly below the lower limit of the normal male range for testosterone 3
- Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels, which distinguish between primary (hypergonadotropic) and secondary (hypogonadotropic) hypogonadism 4, 5
- Serum hormone binding globulin, thyroid stimulation hormone, prolactin, and insulin-like growth factor 1 (IGF-1) levels, which may be measured to evaluate the underlying cause of hypogonadism 6
- Sperm parameters, which may be determined to evaluate the effect of treatment on fertility 6, 7
Timing and Frequency of Laboratory Tests
Laboratory tests should be performed: