Reasons for variances in lab test results

Reasons for variances in lab test results

Advantages and Difficulties of Hormone Testing

There are many reasons why different laboratories may produce different ranges of hormone biomarkers. The reasons can vary and include the following:

  1. Methodological differences: Different laboratories may use different techniques or methods to measure hormone levels, which can lead to variations in results. Some labs use other assays (e.g., RIA, ELISA, LC-MS/MS) that can produce different results.
  2. Different reference ranges: Laboratories may use different reference ranges, values considered normal for a particular biomarker. These ranges are typically based on a population sample of healthy individuals and will vary depending on the selected population.
  3. Population: Laboratories also can be located in diverse regions and serve different people. These demographic and genetic factors can influence the normal range for a biomarker.
  4. Equipment: Different laboratories may use different equipment, which can also contribute to variations in results. Even slight differences in equipment or reagents can lead to variations in results.
  5. Quality control procedures: Quality control procedures vary from laboratory to laboratory and may result in variations in results.

Lab testing assays

Several types of assays can be used for hormone testing, including radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RIA is a highly sensitive and specific assay for measuring hormones in the blood, such as thyroid and androgen hormones.

ELISA is commonly used to measure hormones in the blood, serum, or urine, such as FSH, LH, Testosterone, and Progesterone.

LC-MS/MS is considered a “gold standard” assay in hormone testing. It is ultra-sensitive and specific and is used to measure a wide range of hormones in the blood, including androgen hormones, such as testosterone and estrogen, and peptide hormones, such as human growth hormone and insulin-like growth factor-1.

In addition to these assays, immunoassays based on lateral flow technology, such as POC (Point of Care) testing, are also widely used for hormone testing, such as FSH and LH tests.

It’s important to remember that these variations in results do not necessarily mean that one laboratory’s analysis is more accurate than another’s. Instead, consider the context in which the results were obtained and consult a healthcare professional to interpret your test results. They can provide more information and context to the results and help you understand what they mean for your overall health.

Home hormone testing kits

Home testing kits for hormones can be less accurate than laboratory testing because the sample may not be collected or stored correctly, the assay used in these kits may be less sensitive and specific, and the interpretation of results could be difficult. 

For example, home testosterone testing kits are generally less accurate than tests performed in a lab, as the sample collection and storage method can affect the results. In addition, some of the home testing kits for testosterone use finger-prick, saliva, or blood spot samples, which may not be as reliable as serum or plasma samples collected by venipuncture and processed in a lab. 

The accuracy rate of these home kits can vary from manufacturer to manufacturer and batch to batch, but some manufacturers claim an accuracy rate of up to 95%.

Clinical Laboratory Improvement Amendments (CLIA)

CLIA certification ensures that specific standards and protocols are followed during testing. However, it is vital to note that not all CLIA-approved testosterone assays are conducted using the recommended liquid chromatography-mass spectrometry method as recommended by the Endocrine Society.

For example, the measurement of anti-Müllerian hormone (AMH) levels, which are assay dependent, can be affected by the method used. In cases where both AMH and testosterone levels are being measured for reproductive profiling in women, using DTC (Direct-to-consumer) tests that do not use the appropriate method may lead to inaccurate results

FDA approval vs. FDA clearance

FDA “approval” means that the Food and Drug Administration (FDA) has determined that a product is safe and effective for its intended use. This process involves rigorous scientific testing and evaluation, including human clinical trials. FDA approval is required for certain products, such as drugs, medical devices, and biologics.

FDA “clearance,” on the other hand, is a less stringent process than approval. It applies to products that are considered to be lower risk, such as certain types of medical devices. The FDA uses the 510(k) clearance process to evaluate these products, demonstrating that they are “substantially equivalent” to other products already on the market. This process clears many medical devices, such as home diagnostic test kits.

In summary, FDA approval indicates that a product has been determined to be safe and effective for its intended use through a rigorous evaluation process. In contrast, FDA clearance demonstrates that a product is considered lower risk and has been determined to be substantially equivalent to other products already on the market.


The quality of the assays is not the issue at hand. The concern is how the results are being used. Are they being used in line with evidence-based medicine principles? Are they being compared to a widely accepted benchmark? It is crucial to consider the actions taken based on the data.

It is essential to check the kit’s accuracy rate, read and follow the instructions correctly, and always check the results with a healthcare professional.

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