With rising rates of chronic illness and understaffed health services, functional medicine has become an increasingly popular and highly effective healthcare alternative. Functional medicine uses a holistic approach that personalises therapy depending on the individual, and looks to address the root cause of illness rather than simply managing surface-level symptoms.

Functional medicine practitioners use what are known as “functional tests” or “lab tests” to establish a detailed picture of a person’s health and pinpoint the underlying contributing factors to illness. Functional tests have become an essential diagnostic tool for practitioners and patients alike as they help clarify the patient’s condition and inform the treatment process, guiding the next steps to reestablishing good health.

What Are Functional Lab Tests?

When you are feeling unwell, the most important first step is to find out what the cause is. Functional lab tests cut out the guesswork by looking at a wide range of pathogenic, nutritional and biochemical markers throughout the different systems in the body. These tests are highly effective at identifying imbalances and specific problem areas, and cover a broad range of symptoms and conditions including:

  • Autoimmunity
  • Cardiovascular issues
  • Fertility
  • Food allergies and intolerances
  • Gut health – e.g. bloating, acid reflux, indigestion, IBS, IBD, SIBO, leaky gut, Chron’s
  • Hormonal imbalances – thyroid, adrenals, menopause
  • Metabolic conditions
  • Skin conditions – e.g. eczema, psoriasis, rosacea

What Is The Difference Between A Functional Test And A Standard Blood Test?

Standard blood tests arranged via your doctor are a useful first step towards getting a general picture of what is going on in your body, however, getting face-time with GPs in the UK is becoming increasingly difficult, and not all GPs are willing to run certain tests.

Moreover, standard blood tests tends to lack the specificity needed to pinpoint exactly where your system is off, and can overlook the fact that your health issues may be caused by, or having an effect on, other systems in your body that are not accounted for in that test. Functional testing looks at more comprehensive markers to assess all the necessary parameters that could be affecting your health.

For example, standard tests for thyroid related issues assess a thyroid marker called TSH, however, this test only points to general dysfunction of the thyroid. Functional testing assesses additional thyroid markers (total and free T3 and T4, T3 uptake, reverse T3) that can specifically indicate where the dysfunction is coming from.

How Do Functional Medicine Lab Ranges Differ From Standard Test Ranges?

Standard lab reference ranges tend to be wide meaning that disease progression is more likely to go undetected. Functional lab tests, on the other hand, usually have much narrower ranges that represent optimal health rather than a standard range based on the average population. This means that markers that indicate dysfunction can be detected early on, giving you and your practitioner a greater chance of reversing or stopping disease progression altogether.

How Does The Functional Testing Process Work?

The majority of functional tests can be taken by yourself at home collecting bloodspot, urine, saliva, breath or stool samples, and the overall process is simple.

1. Free Discovery Call / Initial Consultation

A functional medicine practitioner will assess your medical history and symptoms to understand your unique case, then recommend the most appropriate test for your needs.

2. Order Your Test

Tests can be ordered directly via your practitioner and sent to your preferred address. Tests usually arrive within 2-5 days depending on the lab.

3. Take And Return Your Test

Tests come with easy-to-follow instructions but if you have any questions, your functional medicine practitioner can guide you through the process of how to collect your sample and return it to the lab.

4. Test Analysis And Treatment Plan

Once your test has been processed, the lab will send your results to your practitioner for analysis.

During a consultation, your practitioner will translate and explain the findings for you. These findings can provide a lot of insights into your health and the causes of your condition, and in turn, this information can be implemented into your personalised nutrition and lifestyle plan for more targeted and effective treatment.

Book a Free Discovery Call

Discuss your health concerns with a practitioner to see how functional medicine can get your health on the right track.

How Do Functional Tests Improve Treatment Plans?

Holistic Assessment

Functional tests evaluate multiple aspects of health, including hormone levels, nutrient deficiencies, gut health, immune function, detoxification capacity, and more. This helps practitioners understand how your different body systems are interacting with each other, and identify root causes rather than treating symptoms.

Personalised Treatment

Functional tests provide detailed scientific information about your unique biochemistry, allowing practitioners to tailor treatment plans specifically to address your imbalances or deficiencies. This individualised approach improves the effectiveness of interventions and leads to better health outcomes.

Early Detection & Prevention

Functional tests can detect imbalances or dysfunctions before they manifest as symptoms or illness. By identifying these issues early on, practitioners can make early interventions with nutrition and lifestyle adjustments to prevent or mitigate the progression of chronic conditions.

Track Progress

Functional tests provide a baseline assessment of your health, and subsequent tests can be used to track your progress over time, allowing practitioners and patients alike to objectively measure improvements and adjust personalised treatment plans accordingly.

Optimise Performance

Functional tests are not limited to diagnosing illness but also help optimise performance in various areas such as fitness and cognitive function. By identifying areas of improvement or optimisation, you can enhance your performance and achieve your goals more effectively.

Patient Empowerment

Functional tests engage you as the patient in your own healthcare by providing you with insights into your health status and deepening your relationship with your practitioner. When you are able to better understand the underlying factors contributing to your condition, you are more able to actively participate in your own treatment plan, leading to increased motivation, better adherence to recommended nutrition and lifestyle changes, and ultimately improved results.

Which Health Conditions Can Functional Tests Identify?

Functional tests cover a broad range of health conditions and symptoms ranging from gut health to food allergies. There are many different types of test, with varying prices, but your functional medicine practitioner will be able to recommend the right one for you based on your case, symptoms and budget.

Functional Tests for Gut Health and Food Allergies

Digestive symptoms such as bloating, acid reflux, indigestion and stomach cramps are amongst the most common complaints in functional medicine practice, and can be caused by gastrointestinal conditions such as IBS, SIBO (Small Intestinal Bacterial Overgrowth) or intestinal permeability (also known as ‘leaky gut syndrome’). Functional testing to identify the cause of digestive issues plays an essential part in healing your gut and supporting your gut microbiome.

There are many types of gut health tests, each looking at different biomarkers.

Some of the most common gut health tests are:

 Gut Microbiome Stool Test

A comprehensive stool profile provides valuable insight into your microbial ecosystem, microbe diversity and imbalances, digestive function and intestinal inflammation. This profile can reveal important information about the root cause of many common gastrointestinal symptoms as well as non-GI conditions.

SIBO Breath Test

SIBO breath testing assesses hydrogen and methane gases to evaluate for SIBO or intestinal methanogen overgrowth (IMO). Bloating, gas, diarrhoea, and constipation are common symptoms of SIBO.

Food Sensitivity Test

IgE and IgG antibody assessments are bloodspot tests that can help identify problematic foods or allergens by measuring antibodies to commonly eaten foods and environmental antigens. Identifying reactive foods and specific triggers helps tailor your treatment plan as their removal from your diet and lifestyle often results in symptoms resolving.

Functional Tests for Hormonal Health

Hormonal imbalances can cause health issues from adrenal fatigue, inflammation, diabetes, obesity and sexual dysfunction to heart disease.

Some of the most frequently used hormonal tests are:

Adrenal Stress Profile

This test assesses the Hypothalamic-Pituitary-Adrenal (HPA) axis using carefully timed salivary samples of the hormones cortisol and DHEA. Imbalances in adrenal hormoneas can have a wide range of symptoms including fatigue, mood disorders, weight issues, and cardiovascular disease.

Comprehensive Hormone Panel

This test assesses the Hypothalamic-Pituitary-Adrenal (HPA) axis using carefully timed salivary samples of the hormones cortisol and DHEA. Imbalances in adrenal hormones can have a wide range of symptoms including fatigue, mood disorders, weight issues, and cardiovascular disease.

DUTCH Complete Test

This test provides a unique assessment of sex and adrenal hormones in both women and men by assessing dried urine. It can provide insights into conditions such as premenstrual syndrome, PMDD, PCOS, menopause, infertility, weight gain, fatigue, low libido, sleep issues and mood disorders in women. As well as infertility, weight gain, fatigue, low libido, sleep issues, mood disorders and prostate issues in men.

Methylation Panel

This test assesses critical biochemical methylation pathways, and can uncover needs for nutritional support such as amino acids, vitamins, and minerals in people with: cancer risk, cardiovascular disease, chronic fatigue, fertility issues, psychiatric and mood disorders, and neurological disorders. Knowing this can help guide dietary and nutraceutical treatment plans.

Thyroid Panel

Thyroid hormones are essential and primary regulators of the body’s metabolism. Hormone imbalances can affect virtually every metabolic process in the body, exerting significant effects on mood and energy level. This test reveals imbalances that often go undetected with standard blood tests by thoroughly analysing levels of TSH, free T4, free T3, reverse T3, anti-TG antibodies, and anti-TPO antibodies to assess central and peripheral thyroid function, as well as thyroid auto-immunity.

Functional Tests for Nutritional Deficiencies

Nutritional imbalances are often root cause contributors to illness. Correcting these imbalances can result in improved health and well-being, as well as disease prevention.


This test provides a comprehensive nutritional assessment that can be used to address a wide range of concerns and health conditions. The NutrEval is both a blood and urine profile that evaluates more than 125 biomarkers and assesses your body’s need for 40 antioxidants, vitamins, minerals, essential fatty acids, amino acids, digestive support, and other select nutrients.


Provides a combination of nutritional tests that analyse key nutritional biomarkers. A first morning void (FMV) urine collection, with optional add-on bloodspot finger stick and buccal swab, this test is a non-invasive, patient-friendly way to assess the functional need for antioxidants, B-vitamins, minerals, digestive support, fatty acids, and amino acids. Test findings allow practitioners to target nutritional therapies to meet your specific health needs.

Functional Tests for Cardiovascular Health

Cardiovascular assessment is essential to prevent or reverse serious metabolic conditions.

Cardio Check

The Cardio Check Profile is an advanced assessment of lipids and cardiometabolic analytes to assess cardiovascular risk factors. It combines conventional and functional laboratory biomarkers to provide clinically actionable insights. Biomarkers assessed include: Apo B/Apo A1 ratio, TC/HDL ratio, Lp(a), LDL, homocysteine, total cholesterol, triglycerides, hs-CRP, HDL, Apo A1 and Apo B.


If you are feeling unwell and don’t know why, functional tests can provide the answers you’ve been looking for.

At Nutrition Diets, we specialise in identifying and correcting imbalances in our clients’ health using the functional medicine approach: balancing personalised nutrition and lifestyle plans, one-to-one therapy and at-home functional testing.

We offer thorough clinical assessment via easy and convenient online consultations. Getting started is simple and free. Take action today to get your health back on track.

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