Long Covid
Long COVID blood test Plymouth
A long COVID blood test Plymouth helps identify treatable causes of persistent symptoms following COVID-19 infection. At Tamar Health, we offer a comprehensive screening panel that includes full blood count, inflammation markers (CRP), ferritin, D-dimer (clotting marker), thyroid function, cortisol, vitamin D, B vitamins, liver function, kidney function, and HbA1c. Long COVID is complex and there is no single definitive blood test, but this panel screens for common underlying treatable causes and rules out serious complications.
Understanding long COVID and what testing can reveal
Long COVID describes persistent symptoms occurring 4 or more weeks after initial COVID-19 infection. Symptoms vary widely but commonly include fatigue, brain fog, breathlessness, chest pain, palpitations, joint pain, sleep disturbance, and psychological symptoms like anxiety and depression. While long COVID’s exact mechanisms remain under investigation, research shows that some people have persistent inflammation, microclotting, metabolic changes, or viral persistence. Blood testing cannot diagnose long COVID itself, but it can identify treatable abnormalities that contribute to symptoms — such as thyroid dysfunction, nutritional deficiencies, anaemia, persistent inflammation, or metabolic disturbance — allowing targeted management.
What this test measures
This comprehensive screening panel assesses multiple body systems implicated in long COVID, looking for treatable abnormalities that may be driving or contributing to your symptoms. The test is designed to cast a wide net, identifying common but treatable causes rather than aiming for a definitive diagnosis.
| Marker or test | What it measures | Why it matters in long COVID |
|---|---|---|
| Full blood count (FBC) | Red cells, white cells, platelets | Anaemia can worsen fatigue; abnormal white cells may indicate ongoing infection or immune activation |
| CRP (C-reactive protein) | Inflammation marker | Elevated CRP indicates persistent inflammation, which is present in some long COVID patients |
| Ferritin | Iron storage protein; also an inflammation marker | High ferritin may indicate iron overload or ongoing inflammation; low ferritin causes fatigue |
| D-dimer | Marker of blood clotting activity | Persistent elevation suggests microclotting, which some long COVID patients experience |
| TSH and FT4 (thyroid function) | Thyroid hormone and stimulating hormone | Post-viral thyroiditis can occur; thyroid dysfunction causes fatigue, depression, and cognitive symptoms |
| Cortisol | Stress hormone, especially morning cortisol | Long COVID often involves dysregulated cortisol; low cortisol contributes to fatigue and low mood |
| Vitamin D (25-OH) | Vitamin D level | Deficiency is extremely common and worsens fatigue, mood, and immune function |
| Vitamin B12 and folate | B vitamin levels | Deficiency causes fatigue, neurological symptoms, and mood disturbance; important to check |
| Liver function tests (LFTs) | ALT, AST, bilirubin, albumin, GGT | Persistent elevation may indicate ongoing inflammatory hepatitis; rule out other causes of symptoms |
| Kidney function (U&Es) | Creatinine, eGFR, urea, electrolytes | Baseline assessment; electrolyte disturbance can worsen fatigue and cognitive symptoms |
| HbA1c (glucose control) | 3-month average blood glucose | Post-viral metabolic dysregulation can affect glucose control; important for long-term health |
Who should get this test?
This test is for anyone experiencing persistent symptoms 4 or more weeks after confirmed or suspected COVID-19 infection. Common presenting symptoms include profound fatigue disproportionate to exertion (sometimes called post-exertional malaise), brain fog or difficulty concentrating, breathlessness, chest pain or palpitations, joint or muscle pain, sleep disturbance, and mood changes like anxiety or depression. You may have struggled to recover as expected after infection, or symptoms may have gradually worsened weeks later. If your symptoms are affecting your ability to work, exercise, or enjoy daily activities, comprehensive blood testing is worthwhile to identify any treatable contributing factors.
- Persistent fatigue (4+ weeks)
- Brain fog or cognitive issues
- Breathlessness or chest pain
- Palpitations or abnormal heart rate
- Joint or muscle pain
- Sleep disturbance
- Post-exertional malaise
- Anxiety or depression post-COVID
- Poor exercise tolerance
- Difficulty returning to normal activities
What your results mean
Understanding your long COVID results
This test is a screening tool, not a diagnostic test for long COVID. Think of it as investigating what might be driving or contributing to your symptoms. If results come back entirely normal, it doesn’t mean long COVID isn’t real or that your symptoms aren’t valid — it simply means no obvious treatable abnormalities were detected by routine blood work. Some long COVID pathology may not show up on standard tests. Conversely, if we find abnormalities, they may offer clues for management: thyroid dysfunction can be treated, vitamin deficiencies corrected, or inflammation addressed.
Tamar Health clinicians will interpret your results in the full context of your symptom pattern, timeline, and medical history. Common findings include vitamin D deficiency (easily treated with supplementation), anaemia, or thyroid dysfunction. Some patients have elevated inflammation markers or D-dimer levels, which may guide investigation of ongoing inflammatory processes or microclotting. Normal results are reassuring but don’t preclude long COVID; they may indicate the need for specialist referral to a long COVID clinic for more advanced investigation.
What happens at your appointment
When you attend your appointment at Tamar Health in Estover, one of our phlebotomists will take a blood sample. The process is straightforward and takes just a few minutes. No fasting is required for this panel, though it’s always helpful to be well hydrated. Our clinician can discuss your symptom timeline and recovery trajectory, which helps us interpret results properly.
Results typically come back within 24–72 hours. We’ll contact you and can arrange a follow-up consultation to discuss findings and next steps. If abnormalities are found, we’ll advise on appropriate management — whether that’s supplementation, dietary changes, GP follow-up, or specialist referral to a long COVID service. If results are normal, we can still help by discussing symptom management strategies, pacing, and when specialist assessment might be appropriate.
Frequently asked questions
How long after COVID infection should I have this test?
Long COVID is defined as symptoms persisting 4 or more weeks after COVID-19 infection. This is the appropriate time to consider testing. Earlier testing may not reveal the picture, as some abnormalities only become apparent weeks later. If you’re unsure whether you had COVID, our clinician can discuss timing with you.
Will a normal result rule out long COVID?
No. A normal result means no treatable abnormalities were detected on this panel, but it doesn’t rule out long COVID. Some long COVID symptoms arise from mechanisms not detected by routine blood work, such as post-viral autonomic dysfunction or cellular changes. Normal results are still useful — they rule out certain conditions and guide further investigation.
What if my results show vitamin deficiencies?
Vitamin deficiencies are common and treatable. Vitamin D deficiency responds well to supplementation. B vitamin deficiencies can be corrected through supplementation or dietary change. Iron deficiency, if found, warrants investigation of its cause. Correcting deficiencies often helps improve fatigue and overall wellbeing.
Can long COVID be cured with medical treatment?
There is no single cure for long COVID. However, identifying and treating treatable contributing factors — such as thyroid dysfunction, vitamin deficiencies, or persistent inflammation — can significantly improve wellbeing. Pacing strategies, gradual rehabilitation, and symptom-specific treatments are part of a holistic management approach.
Should I be referred to a specialist long COVID clinic?
Specialist long COVID services are available in some areas. Our clinician can advise whether referral would be beneficial based on your results and symptoms. Some areas of England now have NHS-funded long COVID clinics providing specialist assessment and rehabilitation support.
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Book your long COVID blood test in Plymouth
No referral needed. Results within 24–72 hours. From £25 appointment fee. Individual test costs apply — see our blood test price list for details.
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