From the Guidelines
The best time to do testosterone labs is in the early morning, as this is when testosterone levels are typically at their highest and most consistent, according to the American Urological Association guideline 1. When evaluating testosterone deficiency, it is essential to consider the timing of laboratory tests, as testosterone levels naturally fluctuate throughout the day.
- The diagnosis of low testosterone should be made only after two total testosterone measurements are taken on separate occasions, with both conducted in an early morning fashion, as recommended by the American Urological Association guideline 1.
- To ensure accurate results, it is crucial to maintain consistency by getting tested at approximately the same time for all follow-up tests to ensure comparable results.
- Additionally, clinicians should consider measuring total testosterone in patients with a history of unexplained anemia, bone density loss, diabetes, exposure to chemotherapy, exposure to testicular radiation, HIV/AIDS, chronic narcotic use, male infertility, pituitary dysfunction, and chronic corticosteroid use, even in the absence of symptoms or signs associated with testosterone deficiency, as these conditions may be associated with low testosterone levels 1.
- The use of validated questionnaires is not currently recommended to either define which patients are candidates for testosterone therapy or monitor symptom response in patients on testosterone therapy, emphasizing the importance of laboratory testing and clinical evaluation 1.
From the Research
Best Time to Do Testosterone Labs
- The best time to do testosterone labs is in the morning, as testosterone levels exhibit a circadian variation with peak levels in the morning 2.
- Evidence-based guidelines recommend measuring morning total testosterone (TT) levels as the initial diagnostic test for androgen deficiency 2.
- However, it has been suggested that morning blood draw may not be necessary in older men due to a blunted circadian rhythm 2.
- A study found that TT levels measured in blood drawn from 8 to 11 AM differed significantly from those drawn outside this window, with higher levels in the morning 2.
- The study also found that TT levels in blood drawn from 2 to 5 PM and 5 to 8 PM differed significantly from that drawn from 8 to 11 AM, while TT levels from 11 AM to 2 PM and 8 PM to 8 AM did not 2.
- Based on these findings, it may be possible to expand the blood draw time window for measurement of serum TT, but more research is needed to determine the most appropriate blood draw window 2.
Factors Affecting Testosterone Levels
- Testosterone levels can be affected by various factors, including age, obesity, and certain medical conditions such as type 2 diabetes and hypogonadism 3, 4, 5.
- Obesity is a significant risk factor for testosterone deficiency in men, and weight loss can help improve testosterone levels 4.
- Testosterone replacement therapy may be beneficial for men with hypogonadism, particularly those with related comorbidities such as type 2 diabetes and cardiovascular disease 3, 5.
- Lifestyle interventions, such as weight management and exercise training, can also help improve testosterone levels and overall health 6.