Optimal Ranges vs Reference Ranges in Blood Tests

When you get your blood tested, be that with your GP or a private blood test provider, you will receive your results together with reference ‘normal’ ranges. While these ranges are immensely helpful in identifying serious health problems, they do not give you the full picture of your health and wellbeing.

To achieve a holistic understanding of your health and how you can optimise it, ElevateMe provides optimal ranges instead of reference ranges when you do your blood tests with us.

This article will help you understand the difference between reference and optimal ranges and explain why we have chosen to emphasise optimal ranges in our health plans.


What are reference ranges?

Reference ranges are the values usually used by medical professionals to interpret blood test results. These are ranges calculated within each lab on the basis of the results of 95% of the population.

These values can be very helpful in the interpretation of an individual’s health, especially when identifying extreme pathology or making a diagnosis.

A blood result with a list of reference ranges would look like this:

  • Serum Total Protein: 60 – 80 g/L
  • HbA1c: < 42 mmol/mol
  • Cholesterol: < 5 mmol/L
  • Triglyceride: 0.55–1.90 mmol/L
  • LDL: < 3mmol/L
  • HDL: > 1 mmol/L
  • Cholesterol/HDL: < 4

Issues with reference ranges

Although reference ranges are absolutely indispensable in the diagnosis of disease, it’s crucial to understand that they do not define the state of your health. There are certain issues with using reference ranges to achieve your best health.


1. Problems with data collection

When reference ranges are calculated, they are tested on a random large population. Labs do not take into account crucial health factors such as age, gender and health status, let alone the effects of diet, lifestyle and medication.

This method of calculating reference ranges is often unhelpful to understand our health. What is ‘normal’ for an average group of people may not reflect true optimal health. If a certain percentage of the referenced population has increased levels of a deficiency or a health risk such as obesity, it will skew the reference ranges to a range that is not truly optimal. So while your results may be ‘normal’, they might not be ‘optimal’ at all for long-term health.


2. Normal does not mean healthy

Health is also not binary – it is a continuous measure of your wellbeing and absence of disease. It is so much more complex than just the descriptors ‘normal’ and ‘abnormal’.

Patients often come back with bloodwork that is within the normal reference range and yet present all the symptoms of an underlying disorder. This is because there is often overlap between ‘normal’ and ‘disease’ result ranges – this is something that reference ranges cannot account for. Understanding that disease and dysfunction are on a sliding scale is the first step to achieving optimised health.


3. Wide ranges aren’t helpful

Reference ranges are also notoriously wide. This is another reason why many disorders and dysfunctions of the body aren’t diagnosed early enough to take preventative action.

For example, while your bloodwork may come back as normal for a long time, you might lie on the extreme side of that range. This may be a warning sign that something is wrong. But because you have been labelled ‘normal’, your health issues might not be addressed by your medical professional. Before you know it, you have an unexpected health problem that needs to be treated with harsh and expensive treatments.

But wouldn’t it be better to prevent instead of treat? This is something where optimal ranges provide much better insight than reference ranges.


What are optimal ranges?

Optimal ranges are blood test values that are scientifically linked to better future health and higher life expectancy. This means that they don’t only tell you if your blood tests are extremely abnormal, but they also let you know what your blood tests may mean for you in the future.

Within these ranges, there will be a narrow ‘optimal’ value – this is the result that you should be aiming for. They will also identify results that are slightly outside of optimal – this may mean that it would be beneficial to address that specific biomarker. And of course, they will tell you if your results appear to be on the extreme ends of the ranges, which means you might want to talk to your doctor about them.

Optimal ranges are more detailed than reference ranges

Think of optimal ranges as a more detailed analysis than just normal and abnormal. They have more identifiers like very low, low, sub-optimal, optimal, supra-optimal, high and very high. Thus, optimal ranges give you a clearer picture of your health.


Advantages of Optimal Ranges

As we’ve mentioned above, optimal ranges inform you on what aspects of your health can be improved to prevent health conditions and optimise your wellbeing. This means that they will provide you with actionable results that you can get started on working on today!

Optimal ranges are also so much more specific, you can truly understand whether you should start addressing blood test results early on.

For example, when you receive a triglyceride test result, your results may come back slightly higher than optimal. You get professional medical advice on this and decide to make lifestyle changes to help lower this value. After a while, you decide to re-test and find that your triglycerides are now in the optimal range. Great!

However, you may also find that your triglyceride levels are perhaps not improving after you have changed your lifestyle. Possibly they are becoming even higher. This helps you, and your physician, identify a warning that points to an underlying health issue. The physician runs more tests and makes the correct diagnosis early on to start treating the disease before it gets out of hand.

This is how optimal levels create a system of either complete health optimisation or alternatively early diagnosis.


Biomarkers where Optimal Ranges are better than Reference Ranges

We shouldn’t overlook reference ranges for every blood test that we do. However, there are a few blood tests where reference ranges have been shown to be especially unhelpful in aiding people to achieve better long-term health. Let’s take a look at some of the biomarkers where optimal ranges serve especially better than reference ranges.


Vitamin B9

Vitamin B9, also known as folate, is a nutrient that has a very important role in our bodies. Optimal B9 levels are linked to better blood health, as the vitamin is needed for the production of red blood cells in your body. In fact, individuals with sub-optimal vitamin B9 levels often come across symptoms like fatigue, low immunity and even anaemia.

Therefore, it is important to keep track of your vitamin B9 levels to stay healthy. While most labs set a lower limit for normal levels of this vitamin to be around 4 ug/L, there is increasing evidence that this figure is simply too low to reflect long-term health.

Vitamin B9 - Reference range (ug/L)
Vitamin B9 – Reference range (ug/L)
Vitamin B9 - Optimal range (ug/L)
Vitamin B9 – Optimal range (ug/L)

In a large scientific study, researchers found that Vitamin B9 levels below 17 ug/L are associated with increased mortality rates1. Another study of 1,921 people found that the lowest risk of heart disease was seen in people with levels above 9.6 ug/L2.

By optimising your Vitamin B9 levels, you could not only be avoiding all the negative effects of vitamin deficiency but also further improving your health to prevent disease in the future.


Vitamin D

Vitamin D is another biomarker where researchers have found that reference ranges can be unhelpful. Generally, a range of about 25 – 50 nmol/L is used in most labs as the ‘normal’ value with 125 nmol/L as the highest level. This value has been associated with good bone health and a low risk of osteoporosis.

Vitamin D - Reference range (nmol/L)
Vitamin D – Reference range (nmol/L)
Vitamin D - Optimal range (nmol/L)
Vitamin D – Optimal range (nmol/L)

Additionally, vitamin D is essential for many other parts of our health, including our muscle, hormonal and immune health. Researchers have found that the vitamin D values that result in the best outcomes in all these areas of our health are between 75 and 250 nmol/L.

This range, however, isn’t achieved by the majority of the population. This is because it is very difficult to achieve naturally; you usually need some kind of supplement to get to this range3. Therefore, the optimal ranges that could help you improve your long-term health even further are not reflected in your reference range.

You can read more about the importance of a vitamin D blood test here.


Thyroid Stimulating Hormone

Assessment of thyroid-stimulating hormone (TSH), released by the pituitary gland, is an important test for identifying thyroid dysfunction. Most labs advise the range for TSH to be between 0.27 and 4.3 mIU/L, but studies have found that the upper limit of this range may be too high. In fact, many researchers have suggested that the upper limit should actually be as low as 2.5 mIU/L4.

TSH - Reference range (mlU/L)
TSH – Reference range (mlU/L)
TSH - Optimal range (mlU/L)
TSH – Optimal range (mlU/L)

The cause of this misleading reference range lies in the fact that the distribution of results is skewed by individuals with undiagnosed autoimmune thyroid dysfunction. Furthermore, this group represents a large proportion of the population, which means that the reference ‘normal’ ranges are not representative of good long-term thyroid health.

The skewed data means that often, being within the normal TSH range can give you a false sense of security when there are issues with your results that you could be addressing in order to optimise your health.



Triglycerides are highly significant in ensuring better vascular health. For many labs, the normal reference upper limit for triglycerides is 1.7 mmol/L. However, the values that have been linked with the lowest risk of mortality are actually below 1 mmol/L 5.

Triglycerides - Reference range (mmol/L)
Triglycerides – Reference range (mmol/L)
Triglycerides - Optimal range (mmol/L)
Triglycerides – Optimal range (mmol/L)

Additionally, when cholesterol levels are high, as is the case in many patients at risk of vascular disease, triglyceride levels above 0.99 mmol/L have been shown to increase the risk of a heart attack6. Triglyceride levels above 1 mmol/L have also been linked to a higher risk of developing diabetes.

You can learn more about triglycerides and cholesterol here.


Optimal Ranges vs Reference Ranges

In this post, we have summarised just some of the reasons why reference ranges aren’t always helpful on your journey to health optimisation.

Reference ranges can be way too wide to provide you with useful information about your health, apart from the fact that your results fall into 95% of the population. Reference ranges are also often skewed by any trends in the population, such as increasing obesity or increasing prevalence of a disorder.

Optimal ranges, on the other hand, are calculated using thorough studies with large sample groups that aim to find the range at which your health is at its peak. The sample group is designed to not be skewed by any external factors, so you can find the true ‘healthy’ value. It is also much easier to see any lifestyle changes reflected in your bloodwork with optimal values, as their ranges are narrower.


How ElevateMe helps you perform at your peak health

So how do you avoid getting trapped in those mysterious reference ranges? At ElevateMe, we consider it best to continuously monitor your health with regular blood tests.

Our tailored and intelligent health program, together with our optimal ranges and practitioner guidance, is a definite path to optimised health. Our program will help you identify any health issues before they get out of hand, improve your performance every day, and ensure better long-term health with continuous monitoring.

Moreover, with our free health quiz, you can check your health scores and get free actionable health advice today! Take the free health quiz here.  


Did you know? 

Personalised preventative healthcare, where patients get a proactive rather than reactive approach towards preventing health scares, has been found to significantly reduce hospitalisations.

Take an ElevateMe blood test today to capture 21 blood test insights, track your sleep, fitness, energy, metabolism, cognition, mood, and immunity, and get personalised action plans.

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1. Peng, Y., Dong, B. and Wang, Z. (2016b). Serum folate concentrations and all-cause, cardiovascular disease and cancer mortality: A cohort study based on 1999-2010 National Health and Nutrition Examination Survey (NHANES). International Journal of Cardiology, [online] 219, pp.136–142.

2. Giles, W.H., Kittner, S.J., Croft, J.B., Anda, R.F., Casper, M.L. and Ford, E.S. (1998). Serum Folate and Risk for Coronary Heart Disease. Annals of Epidemiology, [online] 8(8), pp.490–496.

3. Harrington, J. (2018). Vitamin D: What Level is Normal vs Optimal? | ZRT Laboratory. [online] ZRT Laboratory.

4. Biondi, B. (2013). The Normal TSH Reference Range: What Has Changed in the Last Decade? The Journal of Clinical Endocrinology & Metabolism, [online] 98(9), pp.3584–3587.

5. Liu, J., Zeng, F.-F., Liu, Z.-M., Zhang, C.-X., Ling, W. and Chen, Y.-M. (2013). Effects of blood triglycerides on cardiovascular and all-cause mortality: a systematic review and meta-analysis of 61 prospective studies. Lipids in Health and Disease, [online] 12(1), p.159.

6. Tirosh, A., Shai, I., Bitzur, R., Kochba, I., Tekes-Manova, D., Israeli, E., Shochat, T. and Rudich, A. (2008). Changes in Triglyceride Levels Over Time and Risk of Type 2 Diabetes in Young Men. Diabetes Care, [online] 31(10), pp.2032–2037.

Optimal Ranges vs Reference Ranges For Your Best Physical Health - test results

Written by Natalia Glazman

I'm a Biochemistry student at Imperial College, interested in all things immunology and pursuing a career in science communication.


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