From the Guidelines
For a 54-year-old male with suspected low testosterone, I recommend ordering a comprehensive initial bloodwork panel that includes morning total testosterone, free testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, complete blood count (CBC), comprehensive metabolic panel (CMP), lipid panel, hemoglobin A1c, and thyroid-stimulating hormone (TSH). This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of a thorough diagnostic workup to determine the underlying cause of low testosterone symptoms 1.
Key Components of the Initial Bloodwork Panel
- Morning total testosterone: should be measured between 8-10 AM when levels are typically highest
- Free testosterone: essential for determining the bioavailable testosterone
- Luteinizing hormone (LH) and follicle-stimulating hormone (FSH): help differentiate between primary and secondary hypogonadism
- Prolactin: elevated levels can suppress gonadotropin secretion, leading to hypogonadism
- Complete blood count (CBC), comprehensive metabolic panel (CMP), lipid panel, hemoglobin A1c, and thyroid-stimulating hormone (TSH): help identify other conditions that may contribute to low testosterone symptoms, such as anemia, diabetes, or thyroid disorders
Additional Tests to Consider
- Sex hormone-binding globulin (SHBG): if total testosterone is low but free testosterone is normal
- Estradiol: especially if gynecomastia is present
- Prostate-specific antigen (PSA): as a baseline before potential testosterone replacement therapy
Importance of Proper Diagnosis
Proper diagnosis is essential before initiating any testosterone replacement therapy, as it helps determine the underlying cause of low testosterone symptoms and identifies other conditions that may contribute to these symptoms 1. A thorough diagnostic workup can also help minimize the risks associated with testosterone replacement therapy, such as increased coronary artery plaque volume and cardiovascular events 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 The initial bloodwork to order for low testosterone in a 54-year-old male is:
- Serum testosterone levels, measured in the morning on at least two separate days 2
From the Research
Initial Bloodwork for Low Testosterone
To diagnose low testosterone in a 54-year-old male, the following initial bloodwork is recommended:
- Morning total testosterone level by a reliable assay as the initial diagnostic test 3
- Measurement of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to determine whether hypogonadism is primary or secondary 4
- Measurement of free or bioavailable testosterone level in some men, especially if total testosterone is near the lower limit of normal or if sex hormone-binding globulin (SHBG) abnormality is suspected 3
Rationale for Bloodwork
The recommended bloodwork is based on clinical practice guidelines that suggest making a diagnosis of androgen deficiency only in men with consistent symptoms and signs and unequivocally low serum testosterone levels 3. The measurement of LH and FSH is important to determine the underlying cause of hypogonadism, which can be primary (testicular failure) or secondary (hypothalamic-pituitary dysfunction) 4, 5.
Additional Considerations
In addition to the initial bloodwork, it is also important to consider other factors that may affect testosterone levels, such as:
- Time of day: Testosterone levels typically peak in the morning and decline throughout the day 6
- Age: Testosterone levels decline with age, and hypogonadism is more common in older men 7
- Medical history: Certain medical conditions, such as pituitary or testicular disorders, can affect testosterone levels 5
- Medications: Certain medications, such as steroids or opioids, can affect testosterone levels 7