How results are interpreted

In short

Each result is compared with a reference population. Most markers use reference ranges from NHANES, the CDC’s national population survey; the remaining markers use an internal validation study of 1,000 adults.[2][3] Your result is then placed in one of three percentile bands: below the 75th percentile, 75th to 95th percentile, or above the 95th percentile.[2]

Last reviewed: October 25, 2026. Prepared by Intrinsic Prism, which sells an at-home toxin test. For how each marker is measured in the lab, see How our test is measured.

Where the reference ranges come from

• NHANES. The National Health and Nutrition Examination Survey is run by the CDC’s National Center for Health Statistics. It is a national survey that includes health exams and laboratory tests of people across the US, so its results show how common different levels are in the general population.[3]
• Internal validation study. The remaining markers use the laboratory’s internal validation study, in which the levels of 1,000 adults were measured.[2]

Either way, a reference range describes how common a level is in a population. It is not a safety limit: finding a chemical in blood or urine shows exposure, and does not by itself mean it is causing harm.

The three percentile bands

A percentile tells you where your result falls compared with the reference group. If your result is at the 80th percentile, 80 out of 100 people in that group had a lower level and 20 had a higher one.

• Below the 75th percentile. Your level is lower than the level of at least 3 in 4 people in the reference group. This is the range most people in that group have. It does not mean zero exposure.
• 75th to 95th percentile. Your level is higher than that of most of the reference group; about 1 in 5 people in that group fall in this band. It is worth a closer look: consider likely everyday sources and whether a repeat test later would help.
• Above the 95th percentile. Your level is higher than that of 95 in 100 people in the reference group. It is among the highest in that group. Review possible sources and discuss the result with a healthcare provider.

These bands are for education. They do not diagnose a condition, and they are not medical advice.

What a band can and cannot tell you

• It compares, it does not diagnose. A high band shows your level is unusual for the reference group. It does not show that the substance is causing a symptom.
• It is a snapshot. One sample reflects exposure around the time you collected it.
• It does not name the source. A result does not by itself identify the food, product, building or date that caused the exposure.
• Provoked samples read higher. The reference ranges describe unprovoked samples. If a chelating or “provoking” agent is taken before collection, levels can look higher than they would otherwise.[2] See provoked vs unprovoked testing.

What our report, protocol and guidance add

The bands are the starting point. Around them, the Intrinsic Prism package includes:

• A personalized test report with clear explanations, AI analytics and potential exposure sources.
• Clinician-reviewed result flags.
• A personalized protocol with clear next steps for lifestyle, diet, water, air, environment and detoxification.
• 24/7 guidance through the whole process.

Read Understanding results and next steps for how to work through a report.

See a report and order

Want to see how results are laid out? Open What we Test and select Sample Report; we email you a secure link to the sample report.

Curious how each number is produced? Read How our test is measured.

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FAQ

Where do the reference ranges come from?

Most markers use reference ranges from NHANES, the CDC's national population survey. The remaining markers use an internal validation study of 1,000 adults.

What does below the 75th percentile mean?

Your level is lower than the level of at least 3 in 4 people in the reference group. It is within the range most people have, but it does not mean zero exposure.

What does the 75th to 95th percentile band mean?

Your level is higher than that of most people in the reference group; about 1 in 5 people in that group fall in this band. It is worth considering likely everyday sources.

What does above the 95th percentile mean?

Your level is higher than that of 95 in 100 people in the reference group. Review possible sources and discuss the result with a healthcare provider. It is not a diagnosis.

Is a high percentile a diagnosis?

No. A percentile compares your level with a reference population. These are laboratory-developed tests that are not FDA-cleared, and results are educational, not a diagnosis.