Clinic appointment
Lactose Intolerance Gene Test
A genetic test for common gene variants linked to lactase persistence, the ability to keep digesting lactose into adulthood.
- Doctor-reviewed results
- Laboratory analysis
- 10+ working days from lab receipt
- No fasting required
What’s included
Included tests listed below
Lactase persistence gene variant
Looks for the common genetic variants the laboratory tests that are linked to lactase persistence, the ability to keep digesting milk sugar (lactose) into adulthood. It shows an inherited tendency, not how well you digest lactose now.
Overview
Many adults make less lactase, the enzyme that digests milk sugar (lactose), after childhood. Whether you keep making it is largely inherited. This test looks at the common lactase persistence variants that the laboratory tests. It can show whether you have an inherited tendency to lactose intolerance, which a doctor reads alongside your symptoms. It does not diagnose the cause of your symptoms, and other variants and other conditions can also affect how you digest dairy. Your genes do not change, so it only needs doing once.
It can show whether someone carries the genotype linked to lactase persistence, or to a tendency to lactose intolerance in adulthood, which a doctor reads alongside long-standing symptoms after dairy. It does not measure how a person actually digests lactose and does not diagnose the cause of their symptoms.
Who this is for and who it isn’t
Who it’s for
- Adults aged 18 and over
- Anyone with bloating, wind or loose stools after dairy
- People who want to know whether an inherited tendency could be part of the picture
Who it isn’t for
- It shows an inherited tendency, not how much lactose you can actually tolerate, and it does not diagnose the cause of symptoms. It looks only at the common variants the laboratory tests, so a result that does not show the tendency does not mean lactose is not the cause. Lactose intolerance can also be temporary after a gut infection, or happen alongside conditions such as coeliac disease, which this test does not detect.
- Symptoms with weight loss, blood in your poo, or changes in your bowel habit that last three weeks or more need a GP.
- Anyone with a new, severe or worsening symptom: contact your GP or call NHS 111. A test you buy today is not a substitute for being examined.
Common reasons people choose this test
- Bloating, wind or cramps after milk, cream or ice cream
- Symptoms that improve when dairy is cut down
- Lactose intolerance in the family
- Wanting to know whether an inherited tendency could be part of the picture
These are reasons people choose to test, not signs that something is wrong. A result is one part of a picture your doctor puts together with your history and an examination.
What your result looks like
Every result is shown with the unit and the reference range exactly as the laboratory reported it, with the doctor’s note underneath.
- Lactase persistence gene variant
- Result
- n/a
- Range
- on your report
| Marker | Result | Units | Range | Flag |
|---|---|---|---|---|
| Lactase persistence gene variant | n/a | n/a | on your report | n/a |
Values above are examples. Your report shows your own results with the laboratory’s units and reference range for your age and sex, reviewed, signed and released by a GMC-registered doctor.
How it works
- You book your appointmentA trained clinician takes your sample at one of our London clinics. Nothing to do at home.
- The clinician takes your sampleA single clinic blood draw by a trained clinician
- The laboratory analyses itYour sample is processed for the measurements included in this test. Lab processing typically takes 10+ working days from receipt of your sample.
- A doctor reviews and releases itA GMC-registered doctor reads every result and signs the report before it reaches you.
- Sample
- Clinic blood draw
- Preparation
- No fasting required
- Who it's for
- Any sex · ages 18+
How to prepare
What we can and can’t tell you
This is a genetic predisposition, not a diagnosis. A person with the non-persistence genotype may still tolerate dairy comfortably, and a person with the persistence genotype can still have symptoms after dairy from secondary lactase deficiency, coeliac disease, irritable bowel syndrome, a cow's milk protein allergy or infection. It does not measure actual lactose digestion, so it cannot replace a lactose tolerance or hydrogen breath test where a functional answer is needed. The test looks only at the common variants the laboratory tests, and other variants linked to lactase persistence exist, so a result does not tell the whole story for everyone. It does not diagnose any bowel condition, and it should never be a reason to put off seeing your GP about persistent gut symptoms, unexplained weight loss or bleeding. It does not tell anyone how much dairy they can tolerate.
The reference range beside each result is the laboratory’s own. A result in range is not a clean bill of health and a result outside it is not a diagnosis. Most ranges cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one range. No test result replaces an examination or your own doctor’s judgement, and none of these panels is a cancer screening programme.
Read the full note
A genetic test is not reported against a normal range. It looks only for the specific variants this test covers, so a result that does not show the tendency does not mean lactose is not the cause of your symptoms, and a result that does show it is an inherited tendency, not a diagnosis. Your genes do not change, so there is no need to repeat it, but it also says nothing about how your body digests lactose today.
If you have symptoms that are new, severe or getting worse, contact your GP or NHS 111 rather than waiting for a result. In an emergency call 999.
Frequently asked questions
If my result shows the tendency to lactose intolerance, do I have to give up dairy?
Not necessarily. The NHS says most people with lactose intolerance can manage their symptoms by having smaller amounts of foods that contain lactose. Talk to your GP or a dietitian before cutting foods out. The reviewing doctor explains what your result means in practice.
Is this the same as a milk allergy?
No. Milk allergy is an immune reaction to milk protein and can be serious. This test is about digesting milk sugar.
Who is this test most useful for?
Adults who get symptoms after dairy and want to know whether an inherited tendency could be part of the explanation, and people with a close relative who has lactose intolerance. It is one piece of information, and it does not replace advice from your GP or a dietitian if symptoms are persistent.
How long do results take?
The laboratory typically takes 10+ working days from receiving your sample. This does not include kit delivery, sample collection or return postage. A doctor reviews your results before they are released.
Can I choose a home kit or a clinic?
This test is a clinic blood draw, as it needs a venous sample for accuracy. We arrange a convenient appointment for you.
Is a doctor involved?
Yes. Every result is reviewed by a GMC-registered doctor who signs it off and explains what it means and what to do next.
Is it confidential?
Your results are available through your secure patient portal. Our privacy policy explains how your information is handled and when it may be shared to provide your care.
What happens to my sample and results?
Your sample is analysed at a UKAS-accredited laboratory (ISO 15189). A GMC-registered doctor then reads every result and signs the report before it is released to your secure portal, so nothing reaches you unreviewed. The report says whether each genetic variant tested for was found or not found, and the doctor's note explains what that means for you, what it does not mean, and what usually happens next, which is most often a conversation with your own GP or a dietitian.
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