Abnormal biomarkers in 2025: UK’s most out-of-range results
Ever wondered which biomarkers are most likely to come back out of range?
Blood tests can reveal early risk patterns (sometimes before symptoms), check your organ function, and help you act on abnormal test results. In most reports, you'll see your results within normal, out of range, and borderline reference ranges. Being outside range doesn’t automatically mean illness, but it does mean a biomarker is abnormal and worth interpreting in context.
This year, we wanted to know which biomarkers were most likely to be out of range for Medichecks customers. So, we've outlined the most common out-of-range biomarkers in 2025, plus a quick guide on what to do next for each biomarker.
- Most common abnormal lipid markers
- Iron and blood cell count abnormalities
- Hormone-related out-of-range results
- Liver, kidney, and blood sugar markers
- What to do if your blood test shows abnormal biomarkers
Most common abnormal lipid markers
1) Total cholesterol is the number one out-of-range biomarker from the mid-30s onwards
- Women: Total cholesterol becomes number one from age 36–40 onwards, rising to over 80% in some older bands.
- Men: Total cholesterol remains commonly abnormal in later life, consistently above ~56% in older age bands.
These findings reinforce how often cholesterol levels come back abnormal on routine lab work, and why lipids are so important to estimating long-term cardiovascular risk.
What to do if your total cholesterol is out of range
- Confirm the full picture: repeat or check a full lipid panel (total, HDL, triglycerides, LDL low density lipoprotein, non-HDL).
- Add the big risk multipliers: family history, smoking, weight, diabetes risk, and blood pressure strongly affect overall risk of heart disease and cardiovascular disease.
- If repeatedly abnormal: discuss options for therapeutic intervention (often these will be lifestyle first, then medication when clinically appropriate).
2) ApoB:ApoA ratio is a hidden lipid driver — especially in men
ApoB:ApoA appears as a top abnormal marker across many male age bands and repeatedly in women too. It can add insight beyond standard cholesterol results because it relates to transporting lipids in the bloodstream.
What to do if your ApoB:ApoA ratio is out of range
- Compare with LDL and non-HDL cholesterol to understand risk and levels in the blood.
- If your LDL looks fine but ApoB-related markers are abnormal, consider deeper interpretation with a clinician.
- If you have strong family history of heart disease / cardiovascular disease, prioritise a follow-up even if you feel well.
3) Non-HDL cholesterol becomes commonly out of range in midlife and beyond
Non-HDL cholesterol often rises with age and is a useful measure alongside LDL.
What to do if your non-HDL is out of range
- Treat it as a practical target marker for reducing cardiovascular risk.
- Focus on lifestyle levers that reliably shift lipids: fibre, activity, weight management, sleep, and alcohol moderation.
- Consider repeating if the test was taken during illness, after any recent major diet changes, or under unusual conditions.
4) Lp(a) is often abnormal across ages (inherited cardiovascular risk biomarker)
Lp(a) shows up often across age bands, suggesting many people discover inherited risk only when they test.
What to do if your Lp(a) is out of range
- Lp(a) is largely genetic — diet changes may not shift it much.
- Focus on what you can change: your LDL/non-HDL levels lowering, blood pressure control, smoking cessation, weight and activity.
- Elevated Lp(a) and your family history may change how aggressively other risk factors are managed.
- Once measured, it’s usually stable — repeat testing is not always needed unless advised.
For more about this biomarker, read our blog on why everyone should test their Lp(a) at least once in their lifetime.
Iron and blood cell count abnormalities
5) Transferrin saturation is the most common abnormal biomarker in women aged 18–35
Transferrin saturation is the highest out of range biomarker in women aged 18–35 — highlighting how iron intake, absorption, and menstrual blood loss can influence results.trans
What to do if your transferrin is out of range
- Don’t interpret it alone: review ferritin, iron, transferrin/TIBC and blood cell counts together.
- If low and you have symptoms like fatigue or heavy periods: consider clinical review before high-dose supplements (the cause of low iron and dose matter).
- If high repeatedly: follow up clinically to rule out iron overload causes.
- After diet/supplement changes, repeat testing can be helpful to assess response.
6) Men over 60: red blood cell indices (MCH) often appear out of range
MCH enters the top ten for men >60. Red blood cell indices can be influenced by iron status, B vitamins such as vitamin B12 or folate, inflammation, or broader health factors.
What to do if your MCH is out of range
- Review the full blood count pattern (Hb, MCV, RDW and other or indices).
- Consider common drivers: iron studies, B12, folate, inflammation markers if relevant.
- If symptoms (fatigue, breathlessness, palpitations) or persistent abnormalities: clinician follow-up is important.
Hormone-related out-of-range results
7) Prolactin is the standout out-of-range hormone in young men
Prolactin is the number one in men 18–25 and remains prominent into the 30s. Temporary increases can happen — but persistent elevation deserves a proper review.
What to do if your prolactin is out of range
- Repeat under calmer conditions: good sleep, avoid intense exercise and sex just beforehand, and minimise stress.
- Review medication and alcohol intake, which can affect prolactin levels in the blood.
- If your prolactin levels are persistently high or you experience any symptoms (low libido, sexual dysfunction, headaches/vision changes): clinical assessment is needed.
To understand more about the causes of a raised result, read our blog on prolactin.
8) Young women often show an abnormal mix: iron markers, testosterone or prolactin, and an emerging lipid risk
Women 18–25 frequently show abnormalities across iron and reproductive hormones, alongside lipid markers such as Lp(a) and ApoB:ApoA.
What to do if your iron, hormones, and lipids are out of range
- If hormone symptoms exist (cycle changes, acne, hair growth/loss, low libido), interpret results using cycle timing and symptoms — not a single number.
- Don’t chase borderline results: repeat to confirm patterns where appropriate.
- If multiple markers cluster out of range, a clinician can help prioritise the most meaningful next step.
9) Thyroid Peroxidase antibodies (TPO) are a consistent out-of-range theme for women from the late 30s onwards
TPO antibodies repeatedly appear in women’s top ten from 36–40 onwards. Antibodies can be present even when thyroid hormone levels are still within range.
What to do if your thyroid antibodies are out of range
- Pair antibodies and thyroid function biomarkers, such as thyroid stimulating hormone (TSH),free T4, and free T3 if clinically relevant). Depending on the pattern of your results, your reporting doctor may advise follow up or further testing with your GP.
- If your thyroid antibodies are positive but your hormones are normal: monitor over time, especially if symptoms develop.
- If you’re planning a pregnancy or are symptomatic: follow up with your GP as soon as you can, as thyroid status can matter more in these contexts.
Abnormal blood sugar biomarkers
Even if HbA1c doesn’t appear in every age-band top ten list, blood sugar control still strongly influences long-term cardiovascular risk.
What to do if it’s out of range
- Confirm with repeat testing and/or fasting glucose if advised.
- Address fundamentals: weight, activity, sleep, alcohol, and dietary pattern.
- If abnormal alongside lipids or high blood pressure, overall cardiovascular risk rises — worth earlier action.
Liver, kidney, and blood sugar markers
Many people focus on one flagged result, but trends matter — especially for liver function and kidney function, where multiple markers together better reflect overall organ function.
What to do if your liver or kidney biomarkers are out of range
- Look for a cluster (more than one abnormal biomarker), not a single mild shift.
- Consider context: recent alcohol use, illness, intense exercise, or dehydration can affect your results.
- If abnormalities persist or are significant: repeat testing and clinical follow-up is the sensible next step. Our doctors will always include follow-up advice in your report if it’s appropriate.
Our guide to liver tests explains more on this.
What to do if your blood test results are out of range
If you’ve taken a blood test and found some abnormal biomarkers, there’s a few things you can do.
You can:
- Take a look at your lifestyle. Could you alter your diet, exercise, sleep, or stress levels and check back in a few months?
- If you are experiencing symptoms, it might be time to schedule a call with your GP.
- Look at your results on a holistic level. Can they be grouped by themes e.g. lipids, iron or blood cell counts, glucose levels, liver function, or kidney function.
- You may want to repeat the test to see if the result is the same the next time.
To make sure you gain a comprehensive look at your health, take a look at our Optimal Health Blood test.
FAQs for abnormal biomarkers and out-of-range blood test results
Q. What does out of range mean on blood tests?
A. It means your test results are outside the lab’s reference ranges. It doesn’t automatically mean something is wrong, but it’s a signal to interpret the result in context and consider a repeat test or follow-up with your GP.
Q. Which blood tests show cardiovascular risk and heart disease risk?
A. A lipid profile can help determine your cardiovascular risk. This includes cholesterol levels, triglycerides, HDL, LDL low density lipoprotein, and non-HDL. More advanced markers like ApoB-related ratios and Lp(a) can refine cardiovascular risk, especially alongside blood pressure and family history.
Q. What should I do if my cholesterol levels are high?
A. It’s a good idea to confirm your full lipid pattern, address lifestyle drivers, and if your cholesterol levels stay high over several blood tests, discuss next your steps and possible therapeutic intervention with your GP.
Q. What blood test results suggest kidney function problems?
A. Kidney function is usually assessed with a combination of markers (often including eGFR or creatinine). Repeat testing and clinical interpretation are important if results remain abnormal.
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