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Monitoring testosterone replacement therapy (TRT) requires more than simply checking your testosterone level. Understanding how tests are performed, what the results mean, and how to collect samples consistently can help you get the most value from your testing.

This guide explains our testing methods, reporting practices, and recommendations for obtaining reliable results.

Laboratory Standards & Accreditation

CLIA/CAP-Certified Testing

All laboratory testing is performed according to rigorous quality standards required for CLIA and CAP-certified laboratories.

These standards ensure that:

  • Testing methods are validated before use
  • Quality control procedures are continuously monitored
  • Results are reported only within validated analytical ranges
  • Laboratory processes meet established regulatory requirements

Because of these standards, certain calculated values may not be reported if underlying measurements fall outside validated ranges.

Method Validation

Our assays undergo validation to ensure accuracy, precision, and reliability. Capillary collection methods are also validated against traditional venous blood collection where applicable.

For estradiol testing, the EasyDraw capillary collection method has been validated against venous serum testing using the same analytical methodology.

Hormone Testing Methods

Estradiol (Sensitive E2)

Testing Method

Sensitive estradiol testing is performed using LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry).

LC-MS/MS is considered the gold standard for low-level estradiol measurement because it provides excellent specificity and minimizes interference that can occur with some immunoassays.

Detection Range

The lower limit of detection (LLOD) for estradiol is: 48 pg/mL

Values below this threshold may not be accurately quantified.

Validation Data

Detailed internal validation studies, assay correlation analyses, and proprietary performance metrics are not publicly available.

Total Testosterone

Testing Method

For EasyDraw collections, total testosterone is measured using an immunoassay-based method.

Upper Reporting Limit

The assay reports testosterone concentrations up to: 2,000 ng/dL

Results above this range are reported as: > 2,000 ng/dL

Samples exceeding this limit are not automatically diluted and re-analyzed to provide a higher numerical result.

Free Testosterone

Direct Measurement vs Calculation

Free testosterone is calculated, not directly measured through equilibrium dialysis.

The calculation incorporates:

  • Total Testosterone
  • SHBG (Sex Hormone-Binding Globulin)
  • Albumin

This approach is commonly used in clinical practice and provides an estimate of biologically active testosterone.

Free Androgen Index (FAI)

The Free Androgen Index (FAI) is also calculated using total testosterone and SHBG values.

Formula: FAI = ((Total Testosterone × 0.0347) ÷ SHBG) × 100

Understanding Your Results

Why Are Some Calculated Values Missing?

In some cases, Free Testosterone or FAI may not appear on your report.

This occurs when SHBG or Total Testosterone falls outside the laboratory’s validated reporting range.

To maintain compliance with laboratory quality standards and ensure accurate reporting, calculated values cannot be displayed when underlying measurements fall outside validated parameters.

Why Do Results Sometimes Differ Between Laboratories?

Differences between laboratories are common and do not necessarily indicate an error.

Potential causes include:

Different Testing Methods

  • LC-MS/MS vs immunoassay
  • Different instrument platforms
  • Different calibration standards

Sample Type

  • Capillary blood
  • Venous blood

Biological Variation

Hormone levels naturally fluctuate throughout the day and can be influenced by:

  • Sleep quality
  • Stress
  • Exercise
  • Illness
  • Nutrition
  • Hydration
  • Alcohol intake
  • Medications and supplements

For this reason, trends over time are often more informative than a single isolated result.

Best Practices for TRT Testing

Standardized Blood Collection Conditions

For reliable and comparable results, blood samples should be collected under consistent conditions:

  • Morning collection (ideally before 10:00 AM)
  • Fasting state (8–12 hours, no calories)
  • Before applying testosterone gel/cream (if applicable)
  • Same relative timing within the injection cycle each time
  • After a normal night’s sleep
  • No intense exercise immediately before testing

Injectable Testosterone

Testosterone levels fluctuate across the injection cycle, with higher levels shortly after dosing and lower levels just before the next injection.

  • Testing around 7 days post-injection generally reflects a near-trough level in many weekly dosing protocols
  • Testing 10–14 days post-injection may underestimate typical on-treatment exposure depending on dose and frequency
  • Choose one consistent timepoint in your cycle and use it for all follow-up testing (commonly trough, just before the next dose)

Testosterone Gels and Creams

For transdermal therapy:

  • Collect the blood sample before applying the daily dose
  • Keep application timing consistent between tests where possible

Factors That Can Affect Results

Results may vary due to short-term physiological and external influences, including:

  • Acute illness
  • Sleep disruption
  • Alcohol intake
  • Recent intense exercise
  • Hydration status

These factors can shift hormone levels temporarily and should be avoided when possible for baseline monitoring.

TRT Monitoring Principles

  • Use consistent sampling conditions and timing to ensure comparability
  • Focus on trends over time rather than single measurements
  • Interpret results alongside symptoms and lifestyle context
  • Differences between assays (e.g., LC-MS/MS vs immunoassay) and sample types (capillary vs venous) can affect absolute values
  • Minor variability between tests is expected and does not necessarily indicate a clinically meaningful change

Where can I learn more?