Reference data
Blood Test Normal Ranges UK: The Cited Reference Table
Published UK reference ranges for 23 of the most-searched blood markers, each attributed to its NHS, NICE or HEART UK source. Use it to see roughly where a number sits, then read it alongside the range printed on your own report.
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed July 2026
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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A reference range is the band of results seen in most healthy adults. It is not a pass or fail line. Below is the published UK range for each marker with its source attached. Reference ranges vary slightly between NHS trusts and private laboratories, so where your own report shows a different range, use that one.
“Is my result normal?” is one of the most common things people ask after a blood test. The honest answer is that a single number rarely tells the whole story. A reference range gives you context: it shows where most healthy adults sit, so you can see whether a result is inside that band, a little outside it, or well away from it. What a result means is a question for the clinician who ordered it, read alongside your symptoms and your wider picture.
Every range on this page is a published UK figure, attributed to its source: the NHS, NICE, HEART UK, the UK Kidney Association or the British Society for Sexual Medicine. None of it is Helvy’s opinion. We have deliberately left out markers whose ranges swing heavily with age, sex, time of day or the specific assay used, because a single “normal” band would mislead more than it helps. If your NHS App shows a word such as “satisfactory” where you expected a number, our guide to what NHS App test result comments mean explains it.
How to read a reference range
A reference range is usually written as two numbers, for example “12 to 22 pmol/L”. Some markers only have one bound: cholesterol and HbA1c have an upper target you want to stay under, while vitamin D and eGFR have a lower threshold you want to stay above. Being just outside a range is common and often means very little on its own, which is why borderline results are frequently repeated before anything more is done. eGFR is the clearest example, because the printed threshold is the same at 25 as it is at 80. We cover what each eGFR band means at your age separately.
Folate is a good example of a marker with one flat adult range, which folate levels by ageunpacks.
Two things matter most. First, units: the same marker can be reported in different units by different labs (haemoglobin in g/L or g/dL, for instance), so always check the unit next to your number. Second, the range on your own report wins. Laboratories calibrate their ranges to their own equipment and population, so a private panel and an NHS trust can quote slightly different bands for the same test.
Why do reference ranges differ between laboratories?
A reference range is not a rule handed down by one authority. Each laboratory builds its own, from results collected in a group of people it considers healthy. The usual method takes the middle 95% of those results and calls that the range.
Two things follow. First, the equipment matters. Different analysers measure the same molecule in slightly different ways, so a lab calibrates its bands to its own kit. Second, the population matters. A lab drawing on one group of people can end up with a slightly different band from a lab drawing on another.
That is why your own report wins. Where the range printed next to your number differs from the figure here, use the one on your report. It was set by the people who ran your sample. It also explains a common surprise: repeat a test at a different lab and the number can shift a little without anything changing in you.
What if my result is just outside the range?
Sitting slightly outside a range is common, and on its own it often means very little. The middle-95% method builds that in. By definition, 1 in 20 of the healthy people used to set a band fall outside it. Measure several markers at once and the chance that one of them lands outside is high.
This is why a borderline number is frequently repeated rather than acted on. What carries more weight is the pattern: how far outside it sits, whether it is moving over time, and whether it fits how you actually feel. Two markers show this especially clearly: CRP, which rises after any recent bug, and urea, which moves with how much you drank and ate. A third, albumin, drifts down with age while the printed band stays put. So does total protein after 60.
“Blood test results can be complicated. Ask to talk to a healthcare professional if you have questions about your results or do not understand them.”
A number is a measurement, not a verdict. Reading one properly needs your history, your symptoms, and a clinician who has both in front of them.
A practical next step, then. Write down the number, the unit, and the range printed beside it. Note when the sample was taken and whether you had eaten. Take all of that to your GP. Those few details change how a result should be read more often than people expect.
Why do some markers have no single normal range?
A few well-known markers are missing from the table below on purpose. For those, one band would mislead more than it helps.
Age is one reason. TSH drifts upward through later life, so an older adult can sit above a young adult’s band and still be age-appropriate. The thyroid levels guide sets out the age-specific figures.
Timing is another. Cortisol peaks shortly after waking and falls through the day, so a value means little without the hour it was taken. That is why the normal cortisol range is quoted for a 9am sample rather than for any time you happen to test. Cycle hormones such as FSH move across the month for the same reason.
Sex and method matter too. Ferritin bands differ for men and women, and results from a full blood count are reported in different units by different labs. Where age, sex, timing or method changes the answer that much, we point you to the guide for that marker instead of printing one band here.
Cholesterol and heart health
Total cholesterol
mmol/L5 mmol/L or below
5.0 mmol/L or below is the general healthy-adult target. Total cholesterol is only part of the picture, and your ideal figure depends on your overall heart-health risk.
Source: NHS / HEART UK
HDL cholesterol
mmol/LMen1 mmol/L or above
Women1.2 mmol/L or above
HDL is the 'good' cholesterol, so higher is generally better. Above 1.0 mmol/L for men and 1.2 mmol/L for women is the usual healthy marker.
Source: HEART UK / BHF
Non-HDL cholesterol
mmol/L4 mmol/L or below
Below 4.0 mmol/L is the usual target for adults without heart disease. Non-HDL captures all the harmful cholesterol in one number.
Source: HEART UK / NICE
LDL cholesterol
mmol/L3 mmol/L or below
Below 3.0 mmol/L is a common target for adults without established heart disease. People at higher risk are often given a lower personal target.
Source: NHS / HEART UK
Triglycerides (fasting)
mmol/L1.7 mmol/L or below
Below 1.7 mmol/L is the usual healthy figure for a fasting sample. A non-fasting sample sits a little higher, so check how yours was taken.
Source: HEART UK
Blood sugar and metabolic
HbA1c
mmol/mol42 mmol/mol or below
Below 42 mmol/mol is the non-diabetic range. Readings of 42 and above are worth discussing with your GP, who reads HbA1c alongside your wider picture.
Source: NICE NG28 / NHS
Thyroid
TSH
mIU/L0.27 to 4.2 mIU/L
TSH is read together with Free T4, not on its own. The pattern between the two is what a clinician interprets alongside your symptoms.
Source: Typical NHS laboratory range
Free T4
pmol/L12 to 22 pmol/L
Free T4 is the thyroid hormone available to your tissues. It is interpreted next to TSH, never in isolation.
Source: Typical NHS laboratory range
Free T3
pmol/L3.1 to 6.8 pmol/L
Free T3 is the active thyroid hormone. It adds detail to a thyroid panel but is read alongside TSH and Free T4.
Source: Typical NHS laboratory range
Vitamins and minerals
Vitamin D (25-OH)
nmol/L50 nmol/L or above
50 nmol/L or above is generally considered sufficient. Between 25 and 50 is often called insufficient, and below 25 is the level treated as deficiency.
Source: NICE / NHS vitamin D guidance
Vitamin B12 (serum)
ng/L200 ng/L or above
Below roughly 200 ng/L is the level where B12 deficiency becomes likely, though ranges vary between labs. B12 is usually checked alongside folate.
Source: NHS laboratory guidance
Folate (serum)
µg/L (ng/mL)3.5 µg/L (ng/mL) or above
Below about 3.5 µg/L is treated as low, and 3.5 to 5.5 is often reported as borderline. Folate and B12 are read together.
Source: NHS laboratory guidance
Ferritin
µg/L (ng/mL)Men30 to 400 µg/L (ng/mL)
Women30 to 300 µg/L (ng/mL)
Ferritin stores iron. A value below 30 µg/L is widely used to confirm low iron stores, though symptoms can begin higher. It also rises with inflammation.
Source: NICE CKS (iron deficiency)
Magnesium (serum)
mmol/L0.7 to 1 mmol/L
Serum magnesium measures the small fraction in your blood, not your total body stores, so it can read normal even when intake is low.
Source: NHS laboratory range
Full blood count
Haemoglobin
g/LMen130 to 170 g/L
Women120 to 150 g/L
Haemoglobin carries oxygen in your red cells. Some labs report it in g/dL (divide g/L by 10), so check the unit on your report.
Source: NHS haematology reference ranges
White cell count
x10⁹/L4 to 11 x10⁹/L
White cells are part of your immune system. The count moves around with recent infection, so a one-off reading near the edge is often repeated.
Source: NHS haematology reference ranges
MCV (red cell size)
fL80 to 100 fL
MCV is the average size of your red cells. It gives a clue about the cause of a low haemoglobin, which is why it is read with the rest of the count.
Source: NHS haematology reference ranges
Liver function
ALT (liver)
U/L7 to 56 U/L
ALT is a liver enzyme. Ranges vary between labs, so use the one on your report. A single mildly raised reading is common and often repeated before anything more.
Source: Typical UK laboratory range
ALP (alkaline phosphatase)
U/L30 to 130 U/L
ALP comes from the liver and bones. Ranges differ by lab, and it naturally runs higher in growing teenagers and in pregnancy.
Source: NHS laboratory range
Albumin
g/L35 to 50 g/L
Albumin is the main protein in blood. It is read as part of a liver and general-health panel, not on its own.
Source: NHS laboratory range
Kidney function
eGFR
mL/min/1.73m²90 mL/min/1.73m² or above
90 or above is the standard normal figure. Between 60 and 89 is common and often normal on its own, without other signs of kidney disease.
Source: UK Kidney Association / NHS
Hormones
Total testosterone (adult male range)
nmol/L8.6 to 29 nmol/L
This is the adult male reference range. Testosterone is best measured on a morning sample. Women have a much lower range, so see the women's guide if this is a female result.
Source: BSSM / UK laboratory range
Inflammation
CRP (C-reactive protein)
mg/L5 mg/L or below
Below 5 mg/L is the usual reference for standard CRP. It rises with any recent infection or injury, so it reflects general inflammation, not one cause.
Source: NHS laboratory range
Labs vary. The figures above are published UK reference ranges, but every laboratory sets its own bands. Always use the range printed on your own report where it differs, and take any result you are unsure about to your GP, who reads it alongside your history and symptoms.
Where do the figures on this page come from?
Every band above carries the name of the body that published it. Most come from the NHS or from NICE guidance. Lipid targets follow HEART UK. Kidney figures follow the UK Kidney Association. The testosterone band follows the British Society for Sexual Medicine.
We chose named UK sources for a reason. Ranges quoted on health sites are often American, and several markers are reported in different units there. Copying those figures across is one of the easiest ways to read a British report wrongly.
The same data drives the on-site results checker and the CSV below, so all three stay in step. Where a source updates its figure, the change lands in one place and flows through to each of them.
Download the dataset
The full table is available as a spreadsheet, with a source column for every range, so journalists, researchers and clinicians can cite it directly. It is published under a Creative Commons Attribution licence: please credit Helvy and link back to this page.
Want to check a specific number against these ranges? The free blood test results checker places a single value against the cited range and tells you where it sits, with no account and no diagnosis.
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