Persistent unexplained symptoms: what a root-cause assessment involves

Who this guide is for

You have been unwell for months, sometimes years. It might be exhaustion, pain, gut trouble, poor concentration, dizziness, palpitations, or several of these at once. You have seen your GP, probably more than once, and perhaps two or three specialists. Each has looked at their part of the problem, found nothing that belongs to them, and sent you back. The blood tests were normal, or nearly normal. You have been told it is stress, or age, or that you will have to learn to live with it.

This guide explains what a root-cause assessment does differently, what it tends to find, where it has limits, and how to decide whether it is worth your money. I have tried to write it so that it is useful whether or not you ever see me.

What 'unexplained' usually means

'Unexplained' almost always means 'not explained by the tests done so far'. That is a statement about the investigation, not about you, and it is a very common position to be in. In a study of new patients at seven outpatient clinics in two south-east London hospitals, just over half of those with a final diagnosis, 52 per cent, had symptoms that were not medically explained, rising to two thirds in the gynaecology clinic. The NHS now tends to use the term 'persistent physical symptoms' rather than 'medically unexplained symptoms', partly because the older phrase was so often heard as 'imagined'. Your symptoms are real. The question is what is driving them.

There are structural reasons people fall through the gaps. Hospital medicine is organised by organ: a cardiologist for the heart, a gastroenterologist for the gut, a neurologist for the nervous system. Someone whose problem spans several systems can be seen by all of them and fully explained by none. A standard GP appointment is ten minutes, which is enough to exclude the dangerous and not enough to take the long history that multi-system symptoms usually need. None of that is anyone's fault. It is simply not what those appointments are designed to do.

How a root-cause assessment works

The most important test is the history, and it is the one that gets squeezed out of short appointments. I set aside two hours for a first consultation, and I read your records, results and intake forms beforehand so that the time goes on you rather than on paperwork.

I use a framework from the Institute for Functional Medicine that organises the history into three questions:

• Antecedents. What made you susceptible? Family history, genetics, early life, previous illness, long-standing patterns of sleep, diet and stress.
• Triggers. What set this off? An infection, a period of extreme stress, a pregnancy, a new medication, an operation, a move into a damp building, the menopause transition.
• Mediators. What keeps it going? Disturbed sleep, inflammation, blood sugar instability, nutrient deficiency, deconditioning, a nervous system stuck on high alert.

Laid out as a timeline, the pattern often becomes visible for the first time: symptoms that began a few weeks after a viral illness, or that worsen in a particular house, or that track the menstrual cycle. That pattern decides which tests are worth doing. I order tests to answer specific questions raised by the history, not as a panel applied to everyone, and I use your existing NHS results wherever they exist rather than repeating them.

What is commonly missed

These are the findings that most often explain symptoms after a 'normal' work-up. None is exotic. All are either missed because nobody looked, or dismissed because the result sat just inside the reference range.

• Iron deficiency without anaemia. A normal haemoglobin does not exclude low iron stores. Ferritin and transferrin saturation do, and low stores alone can cause fatigue, poor concentration and restless legs.
• B12 deficiency with a normal-looking B12. Serum B12 is an imperfect measure. Methylmalonic acid or homocysteine can show a functional deficiency the standard test misses.
• Thyroid problems the TSH alone does not show. A full panel, including free T3 and antibodies, sometimes finds an evolving autoimmune thyroiditis years before it becomes overt.
• Coeliac disease. Common, often atypical, and easily missed. The antibody test is only reliable while you are still eating gluten, which is worth knowing before you cut it out.
• Obstructive sleep apnoea. Not only a disease of overweight men who snore. It fragments sleep, damages concentration and produces exactly the tired-and-foggy picture people describe.
• Postural tachycardia syndrome. Dizziness, palpitations and exhaustion on standing, particularly after a viral illness. It is diagnosed with a simple active stand test in clinic, which is rarely done.
• Joint hypermobility, which is associated with pain, fatigue, gut symptoms and postural tachycardia, and is often not examined for.
• Perimenopause, which can begin years before periods change and produces sleep disruption, anxiety, joint pain and brain fog. Where it looks like the main driver, I will say so and point you to your GP or a specialist menopause clinic, which is where it is best managed.
• Post-viral illness, including long Covid. See the chronic fatigue and long Covid guide.
• Medication effects and interactions, especially where several prescribers are involved and nobody has looked at the whole list.
• Insulin resistance with a normal HbA1c, which a fasting insulin level reveals and which contributes to fatigue, weight change and cognitive symptoms.
• Tick-borne and other chronic infection, where the history points that way. This area is contested, and I apply a strict standard of evidence. See the tick-borne illness guide.

In most people I see, the answer is not one of these but two or three together, each modest on its own. That is the practical case for a root-cause approach: it is built to find combinations, where standard care is built to find a single diagnosis.

When the answer is the nervous system

This section matters, and it is the one most root-cause clinics leave out.

Some persistent symptoms arise not from damage or deficiency but from a change in how the nervous system processes signals: pain amplified by central sensitisation, a gut that has become hypersensitive, or a functional neurological disorder. These are real conditions with recognised features. They are diagnosed on positive findings, not simply because everything else was normal, and they respond to specific treatment, including physiotherapy-led rehabilitation and psychological therapies that work on the nervous system rather than on 'stress' in the everyday sense.

A root-cause approach that pretends every symptom has a laboratory-detectable cause will keep ordering tests. That has costs beyond money. Every additional test brings a chance of a false positive or an incidental finding, and each of those brings more tests and more worry. Part of my job is to say when the investigation has done its work, and to move to treatment even when there is no single abnormal result to point to. I think that is a root-cause conclusion in its own right, not a failure to find one.

Functional medicine and standard care compared

The two are complementary, not competing. I practise both: I work at consultant level in an NHS hospital, and I run this practice. This is how they differ in practice.

If you have been failed by one of these, the other is not automatically the answer. The best results usually come from using both: your GP and specialists for what they do well, and a root-cause assessment for the questions they have not had time to ask.

The trade-offs of going private

I would rather you went in with your eyes open.

• Cost. Consultation fees are only part of it. Testing is often the larger cost, and I give a written estimate before ordering anything.
• It does not replace your GP. Your GP holds your records, prescribes long-term medication and coordinates NHS care. I write to your GP, with your consent, so that the two work together.
• Not for emergencies. A private appointment is weeks away and is not the place for anything urgent. See the next section.
• Uneven evidence. Some things recommended in private functional medicine are well supported; some are not. I will tell you which is which, and which tests I think are a waste of money.
• Continuity. I am a sole practitioner. You will always see me, which is good for continuity and limits how many people I can see.

See your GP first if

Some symptoms need prompt NHS assessment before anything else. Please see your GP, or call 111, if you have any of the following, and call 999 for chest pain, sudden weakness or sudden severe headache.

• Unintentional weight loss
• Drenching night sweats or persistent fevers
• Bleeding you cannot explain, including from the bowel or after the menopause
• A new lump anywhere
• A persistent change in bowel habit, particularly over the age of fifty
• Progressive weakness, numbness, loss of balance or change in speech
• Increasing breathlessness
• Symptoms that are clearly and steadily worsening

If any of these come up on a discovery call, I will say so and point you to the right place rather than book you in.

What it costs and how long it takes

Fees include review of your records before we meet, a written summary and plan afterwards, and email support for a week after the first consultation. Testing is charged separately. The full list is on the fees page.

Time. Most people need several rounds of test, treat and review over three to six months. Some things resolve quickly once found, such as iron deficiency or sleep apnoea. Others, particularly post-viral illness, improve slowly and unevenly. Anyone promising a single fix for long-standing symptoms is overselling.

How to judge any clinic, including this one

Three questions sort most clinics quickly. Who will assess you, and what register are they on? Which tests do they not use, and why? What happens if they find something serious? I have written a fuller set, and an honest comparison of doctor-led, nutritional-therapist-led and team-based clinics, in the guide to choosing a functional medicine clinic.

A discovery call with me costs nothing and takes about fifteen minutes. If I think your problem is better served elsewhere, including by the NHS, I will say so.