Chronic Fatigue and Long COVID: Private GP Assessment, Blood Tests, and Management in London
Last updated: March 2026
The Online GP by The Wellness
If you are experiencing persistent fatigue that does not improve with rest, The Online GP by The Wellness provides thorough GP assessments to investigate the cause, arrange comprehensive blood tests, develop a management plan, issue fit notes where clinically appropriate, and refer to specialist services. Many conditions cause chronic fatigue, and the most important step is identifying the right one. Video consultations start from £250. Fatigue blood panels start from £250. All clinical decisions are at the sole discretion of the assessing doctor. All cases are accepted at the complete discretion of the clinic.
WhatsApp us for a same-day fatigue assessment | Call 020 3951 3428 | Email team@thewellnesslondon.com
Why does chronic fatigue need a proper GP assessment?
Fatigue is one of the most common symptoms presented to GPs in the UK. According to the Royal College of General Practitioners, it accounts for approximately 5 to 7% of all GP consultations. The challenge is that fatigue is a symptom, not a diagnosis. It can be caused by dozens of conditions ranging from easily treatable (iron deficiency, vitamin D deficiency, thyroid dysfunction) to complex (chronic fatigue syndrome, long COVID, autoimmune conditions, sleep disorders, depression).
The danger of self-diagnosing is that a treatable cause gets missed. A patient who assumes they have long COVID may actually have undiagnosed hypothyroidism. A patient told they have chronic fatigue syndrome may have undetected coeliac disease or sleep apnoea. A proper GP assessment with targeted blood tests is the only way to distinguish between these possibilities.
NHS GP appointments for fatigue are often limited to ten minutes, which is insufficient for the detailed history and investigation planning that chronic fatigue requires. The Online GP by The Wellness provides extended consultations of 20 to 30 minutes specifically designed for complex presentations.
Exhausted and not sure why? WhatsApp us for a thorough assessment.
What conditions cause chronic fatigue?
The GP assessment systematically works through the following categories to identify or exclude causes.
Nutritional deficiencies. Iron deficiency is one of the most common causes of fatigue worldwide, particularly in women of reproductive age. According to the WHO, iron deficiency affects approximately 30% of the global population. Vitamin D deficiency affects an estimated 1 in 5 people in the UK according to Public Health England. Vitamin B12 deficiency, folate deficiency, and magnesium deficiency can all cause significant fatigue. These are readily identified through blood tests and are treatable.
Thyroid disorders. Hypothyroidism (underactive thyroid) is a common and frequently underdiagnosed cause of fatigue, affecting approximately 2% of the UK population according to the British Thyroid Foundation. Symptoms include fatigue, weight gain, cold intolerance, dry skin, and cognitive fog. A simple blood test (TSH, free T4, free T3) identifies the condition, and treatment with levothyroxine is highly effective.
Diabetes and prediabetes. Undiagnosed type 2 diabetes and prediabetes can cause fatigue, particularly after meals. HbA1c and fasting glucose testing identifies the condition. According to Diabetes UK, approximately one million people in the UK have undiagnosed type 2 diabetes.
Long COVID (post-COVID-19 condition). Defined by NICE as signs and symptoms developing during or after infection consistent with COVID-19, continuing for more than 12 weeks and not explained by an alternative diagnosis. Common features include debilitating fatigue, cognitive dysfunction (brain fog), post-exertional malaise (symptoms worsening after physical or mental exertion), sleep disturbance, breathlessness, and muscle pain. The Office for National Statistics estimated that approximately 1.9 million people in the UK were experiencing self-reported long COVID symptoms as of early 2024.
Chronic fatigue syndrome (CFS/ME). NICE guideline NG206 defines CFS/ME as debilitating fatigue that is not caused by excessive physical or cognitive exertion, is not significantly relieved by rest, and results in a substantial reduction in activity. Diagnosis requires that symptoms have persisted for at least six weeks in adults (four weeks in children) and that other conditions have been excluded through appropriate investigation. Post-exertional malaise (a worsening of symptoms following minimal physical or mental effort) is a hallmark feature.
Mental health conditions. Depression, anxiety, and burnout are major causes of chronic fatigue. According to the Health and Safety Executive, fatigue is reported by over 80% of people with depression. The GP will screen for these using validated tools (PHQ-9, GAD-7) as part of the assessment.
Sleep disorders. Obstructive sleep apnoea affects approximately 1.5 million adults in the UK according to the British Lung Foundation, with many undiagnosed. Insomnia, restless legs syndrome, and circadian rhythm disorders can all cause fatigue that mimics other conditions.
Autoimmune conditions. Conditions including coeliac disease, rheumatoid arthritis, systemic lupus erythematosus (SLE), and inflammatory bowel disease can present with fatigue as a primary symptom.
Other medical conditions. Anaemia from causes other than iron deficiency, chronic kidney disease, liver disease, heart failure, and chronic infections can all cause persistent fatigue.
What blood tests are needed for chronic fatigue?
The Online GP offers a comprehensive fatigue blood panel from £250, designed to systematically investigate the most common and treatable causes of persistent tiredness.
Standard fatigue panel from £250. Full blood count, ferritin, iron studies, vitamin D, vitamin B12, folate, thyroid function (TSH, free T4, free T3), HbA1c (diabetes screening), liver function, kidney function, C-reactive protein (inflammation marker), and calcium.
Extended fatigue panel from £395. Everything in the standard panel plus cortisol (adrenal function), coeliac screen (tissue transglutaminase antibodies), ANA (autoimmune screening), ESR, magnesium, phosphate, and sex hormones (testosterone in men, oestradiol and FSH in women where relevant).
Specialist add-ons available by request. Epstein-Barr virus serology (for suspected post-viral fatigue), Lyme disease serology, and other targeted tests based on the clinical history.
Blood samples are taken at our Marylebone clinic. Results are typically available within 24 to 48 hours for the standard panel and three to five working days for specialist tests. The doctor reviews the results with you, explains what they mean, and recommends the next steps.
WhatsApp us to arrange a fatigue blood panel
How does a private GP manage long COVID?
There is currently no single cure for long COVID. Management is focused on identifying and treating specific symptoms, pacing activity to avoid post-exertional malaise, supporting recovery, and coordinating specialist input where needed.
The GP role in long COVID management includes a thorough assessment to exclude other treatable causes of fatigue (many patients with long COVID have concurrent conditions that are independently treatable), blood tests to check for nutritional deficiencies, thyroid dysfunction, and inflammatory markers, discussion of pacing strategies (the evidence base supports activity management that avoids boom-and-bust cycles), assessment and management of associated symptoms including brain fog, breathlessness, sleep disturbance, low mood, and pain, fit notes for work if the condition affects your fitness to work (issued at the doctor's clinical discretion, video consultations for fit note assessments from £250), and referral to specialist long COVID services, rehabilitation, respiratory physiotherapy, cardiology, or neurology as clinically indicated.
NICE guideline NG188 (COVID-19 rapid guideline: managing the long-term effects) recommends that patients with suspected long COVID receive a holistic assessment, and that graded exercise therapy should not be offered. The Online GP follows this guidance.
How much does a chronic fatigue or long COVID consultation cost?
Video consultation from £250. An extended consultation (20 to 30 minutes) covering detailed clinical history, symptom assessment, and investigation planning. Suitable for most patients.
In-person consultation from £295. Recommended where physical examination would add diagnostic value.
Standard fatigue blood panel from £250.
Extended fatigue blood panel from £395.
Results review and management plan from £150. The doctor reviews your blood results, discusses the findings, and develops a personalised management plan.
Fit notes issued at the doctor's clinical discretion if your fatigue affects your fitness for work. Included within the consultation fee where clinically appropriate. A fit note is never guaranteed.
Specialist referral letter included within the consultation fee where clinically indicated.
Ongoing management and follow-up from £150 per consultation. Chronic fatigue and long COVID often require regular reviews to adjust the management plan.
Important information
Chronic fatigue requires investigation, not assumption. The GP will not diagnose CFS/ME or long COVID without first excluding other treatable causes through appropriate blood tests and clinical assessment. This protects you from missing a condition that has a straightforward treatment.
All clinical decisions are at the sole discretion of the assessing doctor. This includes which tests to order, what to prescribe, whether to issue a fit note, and whether to refer.
Acceptance of cases is at the complete discretion of the clinic. Final charges are determined by clinical complexity.
All doctors are GMC-registered. The Online GP operates as part of The Wellness, a private medical clinic at 10 Portman Square, Marylebone, London.
If you are experiencing a medical emergency, call 999.
Frequently asked questions about chronic fatigue and long COVID
Can a GP diagnose chronic fatigue syndrome? A GP can make a clinical diagnosis of CFS/ME after excluding other causes through appropriate investigation, in accordance with NICE NG206. This typically requires symptoms to have persisted for at least six weeks and for other conditions to have been ruled out through blood tests and clinical assessment.
Can I get a sick note for chronic fatigue or long COVID? Yes, if the doctor assesses that the condition affects your fitness for work. Fit notes are issued at the sole clinical discretion of the doctor. Video consultations for fit note assessments start from £250.
Is long COVID recognised by employers? Long COVID is increasingly recognised as a legitimate medical condition. The Equality Act 2010 may apply if the condition has a substantial and long-term adverse effect on day-to-day activities, meaning the employer would be obligated to consider reasonable adjustments.
Can blood tests diagnose long COVID? There is currently no single blood test that diagnoses long COVID. Blood tests are used to exclude other conditions and to identify treatable abnormalities that may be contributing to symptoms.
The Online GP by The Wellness 10 Portman Square, Marylebone, London Phone: 020 3951 3428 WhatsApp to book | Book online: thewellness.co.uk
Fatigue consultations from £250. Blood panels from £250. Follow-up from £150. All clinical decisions at the sole discretion of the assessing doctor. All cases accepted at the discretion of the clinic. Final charges determined by clinical complexity.
