This method can be performed easily on an automated robotic platform with a 96-well filter plate attached to a collection plate. However, unlike other methods that involve a separate derivatization step, in this method the derivatization reagent solution is used simultaneously for protein precipitation in one simple analyte extraction step. The enhanced sensitivity is enabled by derivatization to attach a charged moiety to carbon 3 of testosterone using Amplifex™ Keto Reagent. The filter plate method started three months after the individual tube method, therefore, its first quarter (Q1) is concurrent with the second quarter (Q2) of the individual tube method. A summary of method performance results, including a comparison with the CDC method is given in Table 2. In addition, the S/N ratio was evaluated for the lowest calibrator level on four different days and the concentration at which the S/N ratio would equal 10 was estimated. My mood log data is private, so you can’t run it again on my data. Plotting the averages (and perhaps also the variances) for each day could help make the data a bit less noisy… There’s also a potential confounder regarding any other weekly cycles (since injections are roughly weekly, although I’ve shifted the day of the week a bit over time). (I’m not clear on how to test for significance, I’m not very expert on analysis.) Today I put together a notebook in Open Humans analyzing my iMoodJournal mood tracking against the injection times. I’ve been recording when I inject (day and approximate time), because I wondered if there’s any mood effects. It might just be some recent events got me down, but look at this mood tracking data – it’s pretty striking! Good agreement between Sal-T and free-T measurements by immunoassays has been shown in both eugonadal and hypogonadal men, suggesting that Sal-T is a reliable marker of testosterone bioavailability (7, 8). T in saliva is thought to be closely related to the component of circulating T to which tissues androgen receptors are exposed. Saliva contains only the free unbound fraction of T which freely diffuses across capillaries and salivary ducts and is unaffected by saliva flow rates, (4). Over the past decade, DBS sampling has been increasingly used for microsampling across various fields due to its significant advantages regarding ease of sample retrieval, shipment, and enhanced analyte stability . Hematocrit correction and matrix effect evaluations confirmed the robustness of the assay for clinical and research applications. The method showed high precision, with intra‐ and inter‐day coefficients of variation below 10%, and satisfactory recovery rates. Accurate testosterone measurement is essential for diagnosing endocrine disorders such as hypogonadism and polycystic ovary syndrome and for routine testing. Testosterone is a critical hormone involved in regulating various physiological processes in both men and women. This section collects any data citations, data availability statements, or supplementary materials included in this article. The authors would like to acknowledge Stefany Healy and Brian L. Williamson from the SCIEX Diagnostics team for writing the sample preparation robot script of plate shaking and centrifugation. The collection plate (with the collected filtrate) was covered with an adhesive seal and placed in the autosampler of the LC-MS/MS system for analysis. 100 µL of serum or plasma sample, calibrator, or control was then transferred to each individually labeled microcentrifuge vial. Calibrators and controls were prepared in-house using 5% BSA as matrix, which was determined to be free of endogenous testosterone by our assay. The method can potentially be used for plasma matrix from different blood collection tubes (Li-Heparin and K2EDTA). The comparison of serum T and free-T with Sal-T (LC-MS/MS) for both males and females is shown in Figure 4. Two outliers were excluded from the analysis because there was insufficient sample to repeat the test. Sal T analysisThe LC-MS/MS method for measuring Sal-T in males has previously been shown to have good analytical performance (13). The exact timing of sample collection in the morning was not found to be critical because we did not demonstrate a significant difference in results when samples were taken 30 min apart. Sal-T generally show the highest concentrations in the morning and lowest concentrations in the evening which agreed with other LC-MS/MS studies in male subjects (11, 12). The correlation between Sal-T and serum-T for males in this study was similar to that found in other studies (11, 12). This can result in a significantly accelerated decline in muscle mass and strength. An RBC magnesium test can provide an earlier indicator of magnesium deficiency than a standard magnesium blood test. After all, if you can control for these blood values, you can be relatively confident that you’re going to not just be maintaining a reduced rate of biological aging, but also superior overall health. Individual sample information, as well as the measured testosterone concentrations in each sample, is shown in SI Tables 4 and 5. The measured concentrations of the plasma samples are shown on the top of the bar chart. Analysis of 20 pediatric samples, aged 7–18 years, indicated a high correlation between endogenous serum and plasma concentrations (Fig. 8). As a preliminary evaluation, we measured testosterone in 37 matched serum/plasma samples from both genders and a broad age range over two experiments. Percent difference between the CDC reference and SCIEX mean concentration values (ng/dL) throughout the cycle year of the phase 2 HoSt certification program for serum total testosterone.
