The private clinic guide to chronic fatigue and long Covid in the UK

Who this guide is for

If you have been exhausted for months, your GP has run bloods, everything has come back normal, and you have been discharged with a leaflet, this is written for you. It is also for the people who have had Covid, never quite recovered, and are now being told that time will sort it out.

I am a hospital doctor who also runs a private functional medicine practice in Twickenham and Richmond, and online. A large part of what I see is fatigue: ME/CFS, post-viral fatigue, and since 2020 a great deal of long Covid. I am going to set out what a proper assessment looks like, what I test and why, and where the limits of the evidence are. I would rather you knew all of that before you spent money with me or anyone else.

Chronic fatigue, ME/CFS and long Covid: the terms

These overlap heavily and the labels matter less than the pattern. But the definitions do affect what the NHS will offer you, so it is worth knowing them.

ME/CFS (myalgic encephalomyelitis, or chronic fatigue syndrome) is defined in the NICE guideline NG206 by four features present together: debilitating fatigue that is not the result of exertion and is not relieved by rest; post-exertional malaise; unrefreshing sleep or sleep disturbance; and cognitive difficulties. NICE says to suspect it when those features have persisted for six weeks in an adult, and to confirm the diagnosis at three months once other explanations have been excluded.

Long Covid is the umbrella term. NICE NG188 splits it into ongoing symptomatic Covid-19, from four to twelve weeks, and post-Covid-19 syndrome, beyond twelve weeks, where the symptoms cannot be explained by another diagnosis. A meaningful proportion of people with post-Covid-19 syndrome meet the criteria for ME/CFS, and in practice I assess them the same way.

Post-viral fatigue is the older, looser term for the same thing after any infection: glandular fever, influenza, and now SARS-CoV-2. The mechanism is not fully understood. The current research literature, summarised well in the NIH-funded RECOVER programme and in reviews such as Davis and colleagues in Nature Reviews Microbiology, points to several overlapping processes: persistent viral material or reactivation of latent viruses, immune dysregulation and autoantibodies, microvascular and endothelial injury, autonomic dysfunction, and disturbed energy metabolism. In any one person, some of those are likely to matter and others not, which is the whole argument for assessing people individually.

The symptom map

Fatigue is the headline, but it is rarely the only thing, and the other symptoms are often what point to the mechanism. When I take a history I am mapping symptoms against systems.

The point of the map is not to reach a label faster. It is to decide which investigations are worth doing in your case, because the list below is long and not all of it applies to everyone.

What the NHS tests, and why it stops there

NICE NG206 recommends a specific panel to exclude other causes of fatigue before ME/CFS is diagnosed. A good GP will have done most of it:

• Full blood count, urea and electrolytes, liver function, calcium and phosphate
• Thyroid function (usually TSH alone, sometimes with free T4)
• ESR or CRP for inflammation
• HbA1c for diabetes
• Creatine kinase for muscle disease
• Ferritin, and often B12, folate and vitamin D
• Coeliac serology
• Urinalysis

This is a reasonable screen for the conditions that can masquerade as chronic fatigue: anaemia, hypothyroidism, diabetes, coeliac disease, kidney and liver disease, inflammatory disease. If any of it is abnormal, the NHS route is the right one and I will say so.

Where it stops is at 'normal'. A normal panel means those particular diseases are unlikely. It does not investigate mitochondrial energy metabolism, the autonomic nervous system, the hormonal stress axis, chronic or reactivated infection, the gut, nutrient status beyond the basics, or the inflammatory picture in any detail. NHS long Covid clinics vary enormously; some are excellent at rehabilitation and have almost no investigative capacity. That gap is what a private workup exists to fill.

What a comprehensive functional workup includes

Below is the range of investigations I draw on. I want to be clear that I do not run all of it on everyone. The history decides, and I give a written estimate before anything is ordered because testing is the largest cost in this work. I have also marked where the evidence for a test is weaker, because some of what is sold under the heading of functional testing does not earn its price.

Extended blood work

• Full thyroid panel: TSH, free T4, free T3 and thyroid antibodies. TSH alone misses autoimmune thyroiditis in its early stages and says nothing about T4 to T3 conversion.
• Iron studies beyond ferritin: transferrin saturation, and the inflammatory context, because ferritin rises with inflammation and can look normal when iron is actually low.
• B12 with methylmalonic acid or homocysteine, folate, vitamin D, red cell magnesium, zinc and copper. Standard serum B12 is an insensitive test.
• Metabolic markers: fasting glucose and insulin, HbA1c, a full lipid profile with ApoB. Insulin resistance is common, under-recognised, and treatable.
• Inflammatory and immune markers: high-sensitivity CRP, ESR, immunoglobulins, and where the history warrants it, autoantibody screening including ANA and antiphospholipid antibodies.
• Hormonal axis: morning cortisol and DHEA-S, and in women the reproductive hormones interpreted against cycle stage. Perimenopause is a very common unrecognised contributor to fatigue in women in their forties.
• Muscle and cardiac: creatine kinase, NT-proBNP and troponin where long Covid has produced chest symptoms, with onward referral for echocardiography if anything is abnormal.
• Coeliac serology if not already done, and total IgA alongside it so a false negative from IgA deficiency is not missed.

Infection

• Epstein-Barr virus, cytomegalovirus and HHV-6 serology. Reactivation of latent herpes viruses is one of the better-supported findings in long Covid research, and it is also a feature of a proportion of ME/CFS.
• Tick-borne infection serology where there is any plausible exposure history. Lyme disease is a genuine cause of chronic fatigue and it is missed, but it is also over-diagnosed by unvalidated tests, and I have written separately about how I approach that.
• Other chronic infections only where the history points there. I do not run large speculative infection panels.

The gut

• A comprehensive stool analysis where there are digestive symptoms: microbiome composition, markers of inflammation such as calprotectin, digestion and absorption markers, and pathogens.
• A hydrogen and methane breath test for small intestinal bacterial overgrowth where bloating and food reactions are prominent.
• I do not use IgG food sensitivity panels. They measure exposure, not reaction, and they lead people to cut out foods unnecessarily. More on that here.

The autonomic nervous system

• An active stand test in clinic, measuring heart rate and blood pressure lying and then standing over ten minutes. It is simple, it is free, and it identifies postural tachycardia in a large fraction of people with long Covid who have never had it looked for.
• Referral for formal tilt-table testing where the result is borderline or the symptoms are severe.

Sleep

• A structured sleep history, and screening questionnaires for sleep apnoea. Apnoea is common, it produces exactly this picture, and it is very treatable.
• Referral for a sleep study where the screen is positive. I do not treat fatigue seriously in anyone whose sleep has not been assessed.

Tests with weaker evidence, which I use cautiously or not at all

• Organic acids testing for mitochondrial function. It gives an indirect picture of energy metabolism and I sometimes find it informative, but the reference ranges and reproducibility are not to the standard of the blood work above. I treat it as supporting evidence, not a diagnosis.
• Salivary cortisol rhythm across the day. Useful for pattern, poor for absolute values, and the concept of adrenal fatigue that is often attached to it is not a recognised diagnosis. I will explain what I think the result does and does not show.
• Urinary mycotoxin testing only where there is a clear history of water-damaged housing and the wider picture fits. It is not a screening test and I will not order it as one.
• Lymphocyte transformation tests, CD57 counts, and other non-validated infection tests: I do not use them, in line with NICE guidance.

What a Bredesen-style protocol adds

My other main area of work is cognitive decline, using the Bredesen approach, and people are sometimes surprised that it is relevant to fatigue. The relevance is the method rather than the diagnosis.

The Bredesen framework starts from the premise that a chronic condition usually has several contributors operating together, groups them into systems (metabolic, inflammatory, nutritional, hormonal, toxic, vascular, infectious), and works out which are active in a particular person before deciding what to do. That is exactly the discipline that chronic fatigue needs. It is also why the brain fog that comes with long Covid and ME/CFS responds, when it responds, to the same kind of systematic approach: sleep, glycaemic control, inflammation, hormonal contributors, and nutrient status, addressed together rather than one at a time.

What it does not add is any claim that fatigue can be reversed on a fixed timescale. I am careful about that language in cognitive decline and I am equally careful about it here.

What treatment actually looks like

Treatment follows the findings, so it varies. But the shape is consistent, and it is worth knowing before you start.

1. Pacing before anything else. If post-exertional malaise is present, the first task is to stop the boom-and-bust cycle. NICE NG206 is explicit that graded exercise therapy should not be offered to people with ME/CFS, and that any activity plan must be led by the person and kept within their energy limits. I follow that. Nobody in my clinic is told to push through.
2. Sleep. Nothing else works well while sleep is disordered. Sleep apnoea is treated, circadian rhythm is rebuilt, and where medication is needed short-term I will discuss it honestly.
3. Correcting what the testing found. Iron, B12, vitamin D, thyroid, insulin resistance, perimenopause: the unglamorous findings that turn out to matter most. Each has an established treatment.
4. Autonomic support where postural tachycardia is present: fluid and salt, compression, a specific approach to activity, and where necessary medication via the appropriate specialist.
5. Targeted support for whatever the wider testing points to: gut treatment where the stool analysis is abnormal, antiviral or immune strategies where reactivation is convincing, and nutritional support for energy metabolism. I will tell you which of these has good evidence behind it and which is a reasonable trial.
6. Reviewing and adjusting. Progress is uneven and the plan changes. A written plan and scheduled reviews matter more than any single intervention.

A sample patient timeline

This is an illustrative composite, not a real patient, put together to show the shape and pace of the work. Real cases are slower, faster, and messier than this.

1. Week 0A free fifteen-minute discovery call. A woman in her early forties, eighteen months after a Covid infection, still working at half capacity, GP bloods normal twice, discharged from the NHS long Covid service after a course of breathing exercises. We decide the approach fits.
2. Week 1Initial consultation, two hours. Full history, symptom map, activity and sleep diary reviewed. Active stand test in clinic: heart rate rises by 38 beats per minute on standing, which nobody had measured. Clear post-exertional malaise. Written plan for pacing and sleep starts immediately, before any results.
3. Weeks 2 to 5Testing. Extended bloods, viral serology, stool analysis. Sleep apnoea screen positive, so referral for a home sleep study through her GP.
4. Week 6Results consultation. Findings: iron deficiency masked by a normal ferritin, low free T3 with positive thyroid antibodies, fasting insulin well above the optimal range, reactivated Epstein-Barr, and mild sleep apnoea confirmed. Each is explained and each has a plan.
5. Months 2 to 4Iron corrected. Apnoea treated. Dietary changes for insulin resistance. Thyroid discussed with her GP. Fluid, salt and compression for the postural tachycardia. Pacing held to strictly. She reports sleep is better and the crashes are fewer, though energy is only modestly improved.
6. Months 5 to 8Gradual, person-led increase in activity within limits. Cognitive symptoms lift noticeably once sleep and iron are corrected. Working four days a week.
7. Month 12Review. Substantially better, not fully recovered. Still has to manage energy deliberately and still has a bad week after any infection. That is a realistic good outcome, and I would rather describe it than a dramatic one.

What it costs

Chronic fatigue and long Covid are assessed under my functional medicine service. The initial consultation is two hours and the current fee is on the fees page, along with follow-up fees and exactly what is and is not included. Testing is additional and is the largest variable cost; I give a written estimate before anything is ordered, and I try to sequence testing so that the most informative and cheapest investigations come first.

A discovery call is free. If I do not think I can help, I will say so on the call.