Is testosterone testing by dried blood spots an accurate method to screen for low testosterone (“Low T syndrome”)
Yes - many clinical studies have shown that dried blood spot testosterone tests are accurate and helpful in screening for “low T syndrome”
Does it matter when patients take their testosterone test?
Yes - Testosterone levels vary during the course of the day and can be also affected by other lifestyle factors such as exercise and amount of sleep. It is recommended that the test is completed in the early morning and that this remains consistent for any repeat testing.
How should patients interpret the results of the at-home testosterone test?
There are multiple factors that are important to consider when interpreting the results of the at-home testosterone test. It is recommended that all patients consult with a provider to properly understand their results. Some things to consider are:
- Each laboratory has somewhat different “normal reference ranges” for testosterone due to differences in equipment used to process the sample as well as different sample collection methods (i.e. capillary vs. intravenous). The differences between labs’ normal reference ranges can vary by as much as 40% and therefore at-home test results should not be compared directly to test results from commercial labs like Quest, LabCorp or a hospital lab.
Note: Reference ranges are the low and high values that are considered “normal"
- While exact reference ranges may vary, a normal or ”in-range” result at one lab should correlate to a normal or in-range result at another lab. If results are being compared between labs, patients and providers typically focus on whether the patient is “in range” or “low or high” as opposed to the exact result value.
- The easiest way to avoid confusion is to have all of your testosterone tests done with the same lab.
What level of testosterone is considered abnormally low?
The specific level of testosterone that is considered low is typically influenced by a number of factors including: age, time of day, and presence or absence of chronic medical conditions - and whether or not a patient has symptoms consistent with low testosterone. These include: reduced libido, low energy, erectile dysfunction, decreased muscle mass/strength, mood changes, reduced bone mass and hair loss. Patients should always consult with their provider to interpret the results of the at-home testosterone test and their eligibility for testosterone replacement therapy. In some cases, the healthcare provider may want to confirm at-home testing results with results obtained by an in-person blood draw that is processed by a commercial or hospital laboratory.
How does being on testosterone replacement therapy (TRT) affect test results?
The goal of TRT is to bring blood testosterone levels into the normal range and to thereby reduce the symptoms of “low T.” Testosterone therapy can be administered a number of ways including patches, gels, injections, and implants. Regardless of the type of therapy, it typically takes weeks to months for the blood level of testosterone to normalize - but many patients feel changes in their symptoms within 4 - 6 weeks.
Providers should guide patients accordingly on how frequently to check blood levels and consider when each blood test is done in relation to each dose of testosterone medication to accurately understand a patient’s results and its implication for the success of TRT therapy. General recommendations are to:
- Take the blood test the same number of days from each dose of medication
- Take the blood test in the early morning
- Use the same lab each time so that the results can most easily be compared.
- If you are using a testosterone gel, it is important to thoroughly wash the gel off of your fingers after administering the gel.