Test for leaky gut syndrome: what methods are available and what they measure
ca. 27 Minuten
Key points
There is no test that can detect leaky gut syndrome. The reason lies upstream of the laboratory: no distinct condition by that name exists in scientific medicine. Something else can be measured, namely the permeability of the intestinal wall. This is a described phenomenon, not a finding that leads to a diagnosis.
This article examines each method on offer and asks the same three questions about each one: What does it actually measure, what evidence supports it, and what conclusions cannot be drawn from it? The zonulin test gets the most attention because it is the most frequently marketed and because the criticism of it comes from the scientific literature itself.
First, you’ll read what the term means and what has actually been described in research. Then come a comparison of the methods, the zonulin test, two persistent assumptions, the lactulose-mannitol test and how it works, other blood markers, and stool tests. The final section covers who would benefit from an examination, which signs should first be discussed with a doctor, and the limitations of all the methods mentioned.
What to expect in this article
1. What the term leaky gut syndrome does and does not mean
2. Increased intestinal permeability: what has actually been described
3. Methods at a glance: what each one measures
4. The zonulin test and the problem with the detection method
5. Three assumptions surrounding these tests
6. The lactulose-mannitol test: procedure, findings and limitations
7. Other blood markers: I-FABP and LBP
8. What stool tests can answer and where their limits lie
9. What a microbiome test measures—and what it does not
10. Who would benefit from an examination now
11. When an appointment should come before any test
12. Limitations: what none of these methods can answer
13. What matters when considering this question
Frequently asked questions
Sources
What the term leaky gut syndrome does and does not mean
Anyone looking for a test for leaky gut syndrome is looking for proof of a suspicion. The suspicion usually goes like this: the intestinal wall has become permeable, so substances that do not belong there enter the bloodstream, causing fatigue, skin problems, bloating or joint pain. The test is supposed to confirm this chain of events.
The term therefore needs to be clarified before discussing methods. A test can only detect something that has been defined beforehand. Iron-deficiency anemia is a case in point: it has a name, a definition, a laboratory value and a reference range. With leaky gut syndrome, the very first link in this chain is missing.
Documented source
“The term leaky gut syndrome is unknown in scientific medicine.”
Transparent Medicine, University for Continuing Education Krems (Cochrane Austria Center)
Article “Leaky Gut Syndrome: Myth of the Perforated Intestine,” as of December 5, 2017
The same article also explains the practical consequence of this finding. According to this assessment, it is nowhere clearly described exactly how a doctor could reliably identify such a leaky gut syndrome. This means there is not only no definition, but also no testing method against which a test result could even be assessed.
This reference is dated 2017, and that should be noted. The editorial team itself states there that a new search for studies did not change its assessment. Nothing has changed since then that would invalidate this statement: a condition called leaky gut syndrome, with established criteria used to diagnose it, has still not been established.
Key point
Increased intestinal permeability is a measurable phenomenon. Leaky gut syndrome is a term from self-help literature. The first does not imply the second, which is why no test can confirm the second.
Why this distinction is not nitpicking
The difference determines what a measurement means for you. If leaky gut were a diagnosis, an abnormal permeability value would be a finding with consequences: it would lead to treatment whose effect could be assessed using the same value. That is not the case.
An increased permeability value stands on its own. It tells us that the barrier is letting more through at that moment than it does in other people. It does not tell us why, for how long, whether it is causing symptoms, or whether it can be changed. The same number can occur with inflammatory bowel disease, after a gastrointestinal infection, while taking certain medications, or without any apparent cause.
This very ambiguity is why permeability measurements have a place in research and are almost never used in clinical practice. They describe a property; they do not ask a question about the patient.
Increased intestinal permeability: what has actually been described
The intestinal wall is not a solid wall. It is a lined surface made up of a single layer of cells, with connections between the cells that open and close. These connections are called tight junctions. They regulate what can pass between the cells, while nutrients are also absorbed through the cells.
It is well established that this regulation can change. In the chapter on pathophysiology, the S3 guideline on irritable bowel syndrome, published by the German Society for Gastroenterology, Digestive and Metabolic Diseases and the German Society for Neurogastroenterology and Motility, describes increased permeability in colon biopsies from affected individuals and in human studies (DGVS and DGNM, 2021).
The same guideline also describes the molecular pathway behind it. Changes in tight junction proteins, increased proteasome activity, and the resulting accelerated breakdown of the tight junction protein occludin have been described. In addition, increased intestinal permeability is linked there to visceral hypersensitivity, meaning heightened pain perception from the abdominal region.
Observed in a disease does not mean: a disease in its own right
This is where many online explanations change direction. “Increased permeability was measured in people with irritable bowel syndrome” becomes “increased permeability causes the symptoms,” and from there becomes a separate condition with its own name. The first statement appears in the guideline. The second and third do not.
Irritable bowel syndrome itself is the most common diagnosis under which such symptoms are ultimately classified. For Germany, the guideline reports an administrative prevalence of 1.34 percent, determined using routine coding data from a large health insurer, with an incidence of 0.34 percent per year (DGVS and DGNM, 2021). This figure describes how often the diagnosis is actually assigned, not how many people have symptoms.
This has a practical implication for testing. If increased permeability occurs in a disease, but not all affected people show it and not everyone with elevated values has symptoms, then the measurement does not cleanly distinguish the groups. A test that does not distinguish them cannot determine anything.
The methods at a glance: what each one measures
There are essentially three options, and they measure three completely different things. The first measures a protein in blood or stool. The second measures two sugar molecules in urine. The third measures which bacteria are present in stool. Only the second even targets permeability.
The following comparison examines all three according to the same criteria. The “What does not follow from this” row is the most important, because it states what is regularly missing from marketing copy.
| Criterion | Zonulin test | Lactulose-mannitol test | Microbiome test |
|---|---|---|---|
| Sample type | Blood or stool | Urine, after consuming a sugar solution | Stool |
| What is measured | A protein measured using an antibody test | The ratio of two excreted sugars | Composition of the bacterial community |
| Targets permeability | Yes, in principle | Yes, as a functional test | No, explicitly not |
| Evidence for the method | Common test kits do not detect the protein they are supposed to measure (Scheffler et al., Frontiers in Endocrinology, 2018) | Established in research, but interpretation is disputed (Vanuytsel et al., Frontiers in Nutrition, 2021) | Sequencing is established, but interpreting individual patterns is not |
| Role in routine practice | None | Not a standard laboratory method | No diagnostic role |
| What does not follow from this | No evidence of a permeable intestinal wall | No diagnosis, no cause, no treatment decision | No statement about the integrity of the intestinal barrier |
The table answers the question about the method. It does not answer what you should do next if you suspect this may apply to you. There’s a separate article for that: Testing for leaky gut: how to get clarity about your gut health addresses what to do and describes the process through a doctor’s office. This article focuses on the methods and the evidence behind them.
The zonulin test and the problem with the detection method
The zonulin test is the best-selling test in this field, and its history explains why. Zonulin is a protein that has been described as playing a role in opening tight junctions. The idea behind this is intuitive: if this protein opens the connections, then a high blood level should indicate an open barrier.
Zonulin was identified as a precursor of the protein haptoglobin 2, or pre-haptoglobin 2 for short. The commercial test kits used by laboratories and providers work with antibodies intended to bind precisely this molecule. Such an antibody test is called an ELISA, a method that makes a protein visible and measurable through a color reaction.
What the test kits actually bind to
A research group led by Laura Scheffler tested these kits in the lab against the purified target molecule. The results appeared in 2018 in the journal Frontiers in Endocrinology and are unequivocal: the antibody test does not detect pre-haptoglobin 2. Neither the recombinantly produced pre-haptoglobin 2 nor complement factor C3 was detected by the kit.
The same study was able to narrow down what the test binds to instead. According to its conclusion, the zonulin ELISA does not detect pre-haptoglobin 2, but rather structurally and possibly functionally related proteins, with properdin being the most likely candidate. Properdin is an immune system protein with a mass of around 53 kilodaltons and has nothing to do with opening tight junctions.
This means the problem is not a dispute over thresholds, but one that arises before the threshold. A measurement method that detects a different molecule from the one named does not produce a value that is too high or too low. It produces a value for something else.
How review literature deals with it
This finding has since been incorporated into review papers. In Frontiers in Nutrition (2021), Tim Vanuytsel, Jan Tack, and Ricard Farré summarize that the most widely used ELISA tests do not measure zonulin, but complement factor C3 and possibly properdin. Their recommendation to the medical community is to read the existing literature on zonulin as a non-invasive marker for diseases involving impaired barrier function with the utmost caution.
For you as someone buying one of these tests, this means two things. First, an abnormal zonulin level is not evidence of a permeable intestinal wall. Second, a normal zonulin level is no reassurance either, because a test that does not measure the right thing can be wrong in either direction.
Three assumptions surrounding these tests
You come across the following three statements in forums, advertising copy, and consultations. All three sound plausible, and all three fail to hold up to scrutiny.
Commonly claimed versus evidence-based
Commonly claimed
“An elevated zonulin level proves that my intestinal wall is permeable.”
Evidence-based
Common test kits do not detect the target molecule pre-haptoglobin 2, but rather related proteins such as properdin (Scheffler et al., Frontiers in Endocrinology, 2018).
Commonly claimed
“Leaky gut is a diagnosis you can get tested for.”
Evidence-based
The term is unknown in scientific medicine, and no reliable way to establish it is clearly described anywhere (Medizin transparent, University for Continuing Education Krems, as of 2017).
Commonly claimed
“A stool test tells me how tight my intestinal barrier is.”
Evidence-based
A stool microbiome test determines the composition of the gut flora. It does not measure permeability, not even indirectly (mybody®x product page, accessed 28.08.2026).
The third assumption is the most persistent because it sounds least like a claim. After all, a stool test examines the gut, and the intestinal wall is part of the gut. The faulty leap is that a sample from inside the gut describes who lives there, not how the adjacent wall is built.
The lactulose-mannitol test: procedure, what it shows, and its limitations
Of all the procedures mentioned, this is the only one that actually tests permeability as a function. It does not measure a protein and infer permeability from it; instead, it lets two molecules make the journey themselves and checks how much gets through.
Two sugars are used. Lactulose is a disaccharide, mannitol a sugar alcohol. Both are swallowed, neither is metabolized, and whatever passes through the intestinal wall into the blood is excreted by the kidneys and ends up in the urine.
Drink the sugar solution
A measured amount of lactulose and mannitol in water, on an empty stomach. A single dose above 5 g is avoided because the osmotic effect would otherwise alter bowel motility.
Collect urine by time interval
The time window determines the section of the intestine: 0 to 2 hours indicates the small intestine, 2 to 8 hours a mixed region, and 8 to 24 hours predominantly the large intestine.
Measure both sugars
The amount of each sugar that has reached the urine is measured. Measuring sugars in urine is not a standard laboratory procedure and must be specifically validated before use.
Calculating the ratio
What is reported is not the individual amount, but the ratio of lactulose to mannitol. It is intended to account for differences in gastric emptying and kidney function.
The reason for using two sugars rather than one comes down to the size of the molecules. Mannitol, at about 6.7 ångströms, is smaller and is thought to pass through the tiny pores between cells. Lactulose, at around 9.5 ångströms, is larger and is thought to pass through only where the barrier is more open. A higher proportion of lactulose relative to mannitol is considered a sign of increased permeability. This account follows the review by Vanuytsel, Tack, and Farré in Frontiers in Nutrition (2021).
Why the test plays no role in routine practice
The first reason is practical. Measuring sugars in urine is not part of a laboratory’s standard repertoire and must be carefully validated before use, as the same review notes. There is no standard procedure that would make results from two laboratories comparable: the dose, collection period, and measurement method vary, and so do the results.
The second reason carries more weight. According to the same authors, the assumption that the two sugars take different routes through the barrier is supported by only scant evidence. This has led to controversy about the validity and, above all, the interpretation of the lactulose-mannitol test. The ratio is therefore not a value that can simply be entered into a table.
The third reason is the decisive one in everyday practice. Even if the ratio is abnormal, that does not lead to a treatment. There is no established therapy based on this value whose success is measured by it. A test whose result changes nothing is a number with no practical relevance.
Other blood markers: I-FABP and LBP
Alongside zonulin, two other abbreviations appear in test panels. Both come from research, both are occasionally marketed as barrier markers, and both measure something different from what their names in sales copy suggest.
I-FABP stands for intestinal fatty acid-binding protein. It is a protein found inside mature intestinal cells. When these cells die, it is released and can be detected in the blood. Elevated levels have been described in various conditions involving cell damage in the intestine. What is lacking are comprehensive studies validating the marker for a specific question.
I-FABP indicates cell death, not permeability. These are two different processes that may or may not occur together.
I-FABP indicates cell death, not permeability. These are two different processes that may or may not occur together. A barrier can let more through without cells dying, and cells can die while the barrier as a whole remains intact.
LBP stands for lipopolysaccharide-binding protein. The idea is to detect components of bacterial cell walls in the blood, where they should normally be found only in very small amounts. Because these components themselves are difficult to measure, the binding protein is proposed as a proxy. One study found a strong correlation between LBP levels and the lactulose-mannitol ratio, as reported by Vanuytsel, Tack, and Farré in Frontiers in Nutrition (2021).
However, a correlation in a study is not a test for individuals. For a marker to become one, it needs a reference range, a known rate of detection, and guidance on what to do when a result is abnormal. Neither marker has these.
What stool tests can tell you and where their limits lie
Stool tests are the most common approach in this area because they can be done at home and because a stool sample seems like an obvious choice when it comes to the gut. It’s worth dividing them into two groups because they answer different questions.
The first group is inflammation and bleeding markers. They are used in medical diagnostics to distinguish between an inflammatory disease and a functional disorder. They say nothing about permeability, but they answer a question that takes priority when in doubt: whether there is any inflammation or bleeding at all.
The second group is microbiome analyses. They use bacterial DNA sequencing to determine which species are present and in what proportions. This is a technically established method with a clear purpose: it describes a composition. Anyone who reads more into it is reading something into it.
Key point
A stool sample describes the inhabitants of the gut, not the condition of its walls. If you want to know which bacteria are present, a microbiome test is the right choice. If you want to check the permeability of the barrier, it isn’t.
Some providers measure zonulin in stool rather than blood. That doesn’t change what Chapter 4 says, because the problem isn’t the sample material but the antibody. A test that binds the wrong protein in blood won’t bind a more accurate one in stool.
Which bacterial groups show up in a microbiome report and what names like Akkermansia or Faecalibacterium refer to is explained in the mybody®x Gut Encyclopedia. It provides the factual foundation for reading a report without attributing significance it does not support.
What a microbiome test measures—and what it doesn’t
A sentence belongs right at the beginning here, one that a shop would rather not write. A microbiome test measures the composition of the gut flora, not the permeability of the intestinal wall. mybody®x (MYBODY Lab GmbH) does not offer a test that measures intestinal barrier permeability, nor one that diagnoses Leaky Gut Syndrome.
So if this is exactly the measurement you’re looking for, you’re in the wrong place in our product range and need to go through a medical practice or a specialized laboratory. We don’t have information on the cost of such testing outside our own services, so no figure is given here.
A microbiome test can answer a different question, and for digestive complaints, it’s no less important: which bacterial groups predominate, how diverse the community is, and whether any yeasts or fungi stand out. This is a snapshot, not a diagnosis.
Stool sample gut test
Gut Microbiome Test | Complete
Uses DNA sequencing to identify over 1,500 bacterial species, as well as biodiversity, enterotype, stool pH, and yeasts and fungi. Intestinal barrier permeability is explicitly not included: the test does not measure permeability or zonulin. If you’re looking for evidence of Leaky Gut Syndrome, you won’t find it here—and according to current scientific literature, you won’t find it anywhere else either. The test provides a snapshot of the gut flora, not a diagnosis, and does not replace medical evaluation.
Lab analysis 5–10 business days after sample receipt
As stated on the product page; no laboratory name provided; accessed 28.08.2026
Two points left unclear on the product page
The first directly concerns this article. The term Leaky Gut Syndrome appears on the Microbiome Gut Test product page in a list of possible symptoms, alongside irritable stomach and irritable bowel syndrome. It isn’t measured by the test, and the page doesn’t name a method for measuring it either. Anyone who reads the list as a promise of what the test can do is misreading it, and we’d rather say so ourselves than leave it unchallenged.
The second concerns the options. Besides the Complete, there is the Gut Flora Microbiome Test Essential for €129.00, as of 27.08.2026. The product pages don’t document how the two differ in scope: the descriptions are identical, and there’s no comparison of the analyses included. As long as that remains the case, we won’t claim there’s a difference.
Whether a statutory health insurer will cover such a test is a separate question with a separate answer. It’s addressed in the article Microbiome Test and Health Insurance and isn’t repeated here.
Who can benefit from testing now
After eight chapters of caveats, it’s natural to wonder whether anything makes sense at all. The answer depends on what question you want answered. The comparison below presents both sides honestly.
Makes sense for you if …
You want to know the composition of your gut flora and use that knowledge as a starting point for a conversation.
Your symptoms have lasted for weeks, and no one has checked yet whether inflammation or bleeding could be behind them. This requires an assessment by a doctor.
You want a baseline record to compare against in three to six months.
You’re willing to read a result as a description, not a verdict.
Probably not, if …
You specifically want to have the permeability of your intestinal wall measured. This value is not included in the range, and no other test can replace it.
You’re hoping the result will confirm a diagnosis. A microbiome report does not name a disease.
Blood in your stool, unintentional weight loss, fever, or symptoms that wake you at night are involved. In that case, an appointment should come before any self-test.
You are already undergoing medical assessment and are waiting for a result. An additional finding from another source is more likely to make it harder to interpret than to help.
If you’re wondering how an at-home gut test works in practice, what sample collection involves, and how results are presented, you’ll find that in the article At-home gut test. This article focuses on what each method measures.
When the appointment comes before any test
There are signs that determine the order of events. They are not downplayed here, softened with “usually harmless,” or tucked into a subordinate clause.
Blood in your stool should be assessed by a doctor. Unintentional weight loss should be assessed by a doctor. Fever accompanying bowel symptoms should be assessed by a doctor. Symptoms that wake you from sleep at night should be assessed by a doctor.
The same applies to pronounced paleness, exhaustion that gets significantly worse within a few days, and symptoms that are new and rapidly intensify. In all these cases, taking a self-test is the wrong order of steps, regardless of which method it uses.
The reason is simple. An online test answers a question you asked. A medical examination also looks for things you didn’t ask about. That’s exactly the point with these signs.
Chapter at a glance
Blood in your stool, unintentional weight loss, fever and symptoms that wake you at night should be assessed by a doctor first. This applies without exception, regardless of what test someone offers. A self-test cannot speed up or replace this assessment because it only answers the question it was asked.
Limitations: what none of these methods can tell you
None of the methods described makes a diagnosis. A microbiome finding describes a composition, a permeability value describes a property, and a blood marker describes a concentration. None of these descriptions tells you the name of a disease.
None of the methods says anything about the cause. Even if increased permeability were measured perfectly, it would still be unclear what caused it. Infections, inflammation, medications and alcohol are cited in the scientific literature as factors, and the test result does not distinguish between them.
None of the methods provides reliable monitoring over time. That would require standardized conditions and a known variation between two measurements in the same person. Neither is available for permeability tests.
And the point that carries the most weight here: even a perfectly measured result would not open up a treatment option. There is no established therapy based on a permeability value. What guidebooks recommend at this point - individual amino acids, collagen, certain bacterial supplements - is not supported by such a result and is therefore not recommended in this article.
What matters when considering this question
It began with the search for a test to confirm a suspicion. That is precisely where the problem lies: the suspicion has never been defined as a medical condition, and what can be measured is not the condition itself.
Still, more remains than nothing. The symptoms that brought you here are real, and there are tests that can clearly identify the most common causes behind them. The way forward is to ask whether there is inflammation, bleeding or a known intolerance, and that is a question for a doctor's office, not a test kit.
A point rarely made in this discussion: criticism of the zonulin test does not come from outside skeptics, but from the scientific literature itself - and the group that originally developed the zonulin concept was also involved in the 2018 study. When the people who proposed a marker themselves describe the method for detecting it as unsuitable, that is no minor finding. It settles the question.
Frequently asked questions
Is there a test that can detect leaky gut syndrome?
No. The term does not refer to a defined medical condition: it is unknown in scientific medicine, and no reliable method for identifying it has been clearly described anywhere (Medizin transparent, University for Continuing Education Krems, as of 2017). Intestinal wall permeability can be measured as a property. But an abnormal result does not provide a diagnosis or lead to an established treatment.
Does the Microbiome Gut Test Complete measure the permeability of my intestinal wall?
No. A microbiome test measures the composition of the gut flora, not permeability. The Microbiome Gut Test Complete uses DNA sequencing to identify over 1,500 bacterial species, as well as biodiversity, enterotype, stool pH and yeasts. Zonulin, a lactulose-mannitol ratio or another barrier marker are not included, and mybody®x does not offer any other test that measures permeability either.
How reliable is a zonulin test?
Reliability is the first question. A study by Scheffler and colleagues in Frontiers in Endocrinology (2018) shows that the widely used commercial antibody test does not detect the target molecule pre-haptoglobin 2 at all, but related proteins, most likely properdin. Vanuytsel, Tack and Farré recommend reading the literature on zonulin as a barrier marker with extreme caution in Frontiers in Nutrition (2021).
What exactly does the lactulose-mannitol test measure?
It measures how much of two ingested sugars appears in the urine and calculates a ratio from this. The smaller mannitol, at about 6.7 Ångström, is supposed to pass through the tiny pores, while the larger lactulose, at around 9.5 Ångström, passes only through more open areas. A collection over 0 to 2 hours is considered to reflect the small intestine. This is not a standard laboratory test, and the interpretation of the ratio is controversial (Vanuytsel, Tack and Farré, Frontiers in Nutrition, 2021).
Which symptoms should be assessed by a doctor first?
Blood in your stool, unintentional weight loss, fever, and symptoms that wake you up at night. Also, marked paleness and exhaustion that get significantly worse within a few days. In these cases, a self-test is not the right first step, regardless of the method it uses.
Next step
Ask the question that can be answered
mybody®x cannot measure the permeability of your intestinal wall. What can be determined is the composition of your gut flora. The linked article explains what practical steps to take if you suspect a problem and who to contact.
Complete Microbiome Gut Test Testing for leaky gut: the processRead more
You might also be interested in
The action-oriented side of the same question: what to do if you suspect a problem and who to contact.
How a stool sample is collected at home and what an actual test result contains.
A reference guide to the genera and species that appear in a microbiome analysis.
Sources
- Medizin transparent, University for Continuing Education Krems (Cochrane Austria Center): Leaky Gut Syndrome – Myth of the leaky gut (as of 05.12.2017) – medizin-transparent.at
- German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS) and German Society for Neurogastroenterology and Motility (DGNM): Update to the S3 Guideline on the Definition, Pathophysiology, Diagnosis and Treatment of Irritable Bowel Syndrome, AWMF Registration No. 021/016 (as of June 2021) – register.awmf.org
- Vanuytsel T, Tack J, Farré R: The Role of Intestinal Permeability in Gastrointestinal Disorders and Current Methods of Evaluation, Frontiers in Nutrition (2021) – frontiersin.org
- mybody®x (MYBODY Lab GmbH): Product page, Microbiome Gut Test | Complete (accessed 28.08.2026) – mybody-x.com
The verbatim quote defining Leaky Gut Syndrome, the statement that no method for determining it is described, and the note that the assessment remains unchanged are from source [1]. The findings of increased permeability in biopsies, the information on tight junction proteins and occludin breakdown, and the administrative prevalence of 1.34 percent and incidence of 0.34 percent per year are from source [2]. The description of the lactulose-mannitol test, including molecule sizes, collection periods, and dose limit; its classification as not being a standard laboratory procedure; the controversy surrounding its interpretation; and the information on zonulin ELISA, I-FABP, and LBP are from source [3]. The price, scope of analysis, sample type, and laboratory information for the Microbiome Gut Test, as well as the mention of the term Leaky Gut Syndrome in its list of complaints, are from source [4]; processing times follow the general guideline for gut tests. Evidence that the commercial zonulin ELISA does not detect pre-haptoglobin 2 and instead binds properdin comes from the study by Scheffler, Crane, Heyne, and colleagues in Frontiers in Endocrinology (2018); it is attributed in the body text with the authors, journal, and year, and is therefore not included in this list. All sources were accessed and reviewed on 28.08.2026.
mybody®x Editorial & Expert Team
Microbiome and gut science Laboratory diagnostics Nutritional science Blood test interpretation
This article was created by the mybody®x editorial and expert team. The team brings together microbiome and gut science, laboratory diagnostics, and nutritional science. The people who contribute to it are listed on the authors page.
Published on 05.12.2025 · Last updated on 27.08.2026
The content is for general information and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age - the information on your test report is always authoritative.
