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Post-COVID Diagnostics
The work-up identifies which mechanisms drive your Long COVID symptoms: microclots, impaired microcirculation, endothelial damage, immune activation, viral remnants, autonomic dysfunction and mitochondrial impairment. It takes one to two days at the start of the stay, and every value in it is measured again later, so the treatment can be judged by numbers.
You had COVID, and eighteen months later you still cannot climb the stairs without your heart racing. Your primary care doctor ordered the standard panel and found nothing. The Long COVID clinic has a waitlist longer than your patience.
This page lists what the Long COVID program at St. George Hospital measures, why those tests, and what the results decide.
No single test diagnoses Long COVID. The diagnosis rests on the history and on excluding other causes; what a work-up can do is show which mechanisms are active in you. The frustration of "normal" results from conventional blood work while symptoms continue is not a sign that the symptoms are imaginary. Standard panels were not designed to detect the processes that drive post-COVID syndrome.
Those processes have been described in the research literature: fibrin amyloid microclots that resist the body's clot-dissolving enzymes (Pretorius et al., 2021), endothelial dysfunction with altered endothelial biomarkers (Haffke et al., 2022), a persistent loss of capillaries in the skin (Osiaevi et al., 2023), circulating spike protein months after infection (Swank et al., 2023), reactivated Epstein-Barr virus (Rohrhofer et al., 2023), functional autoantibodies (Wallukat et al., 2021) and autonomic disorders such as POTS (Blitshteyn et al., 2021). None of them shows on a routine blood count or metabolic panel.
The post-COVID work-up at St. George Hospital is built to measure these mechanisms. Impaired microcirculation, microclots and endothelial dysfunction are the research direction we work on with Dr. Beate Jaeger, and the symptoms and causes page explains how each mechanism produces the symptoms you feel.
Dr. Beate Jaeger, Chief Physician for internal and laboratory medicine, studies microvascular dysfunction in post-COVID syndrome. The working model is that impaired microcirculation, often invisible to conventional imaging, underlies persistent fatigue, cognitive dysfunction, exercise intolerance and organ-level symptoms in Long COVID.
Microclots, or fibrin amyloid microclots, are abnormal clot structures in the smallest vessels that resist normal fibrinolysis. They impair the delivery of oxygen and nutrients to the tissues, which fits the multi-organ symptoms of Long COVID; a 2022 study described their prevalence next to symptoms and platelet pathology in a Long COVID cohort (Pretorius et al., 2022).
What the hospital does with this model is measure: the microclot burden under fluorescence microscopy, the microcirculation by capillaroscopy and perfusion measurement, and standardized symptom scores, each before treatment and again during and after it. Whether and how far these values move in a given patient is read from the repeat measurement, not assumed. The diagnostic value of the microclot and microcirculation methods is still an open scientific question, and they are used next to established laboratory tests, not instead of them.
The post-COVID evaluation covers six domains to identify the mechanisms driving your symptoms. Each test category produces a value that informs treatment selection and is measured again to follow the course.
Functional microcirculation assessment using capillaroscopy and perfusion measurement to evaluate the smallest blood vessels. This shows impaired microvascular flow that conventional vascular imaging does not detect and matters for exercise intolerance and organ-specific symptoms.
Fluorescence microscopy and coagulation analysis to identify fibrin amyloid microclots that persist in the blood of many Long COVID patients. We assess D-dimer, fibrinogen degradation products and platelet activation markers alongside direct microclot visualization to quantify the clot burden and guide apheresis and anticoagulant decisions.
Immune panel including lymphocyte subsets (CD4, CD8, NK cells), T-cell activation markers, cytokine profiles (IL-6, TNF-alpha, IL-1beta, IL-10), autoantibody screening and complement activation. This shows whether persistent immune activation, immune exhaustion or autoimmune mechanisms are contributing to symptoms, and whether immunoadsorption is worth discussing.
Mitochondrial function through organic acid testing, lactate to pyruvate ratios, CoQ10 levels and oxidative stress markers (glutathione, MDA, 8-OHdG), plus NAD+ status and B-vitamin levels. Mitochondrial impairment is a described mechanism of Long COVID fatigue (Molnar et al., 2024); the mitochondrial page explains the tests.
Autonomic function (heart rate variability, tilt-table testing where indicated), neurocognitive screening and neuroinflammatory markers. Many Long COVID patients have dysautonomia, brain fog and cognitive impairment linked to neuroinflammation and microvascular dysfunction in the central nervous system. Where post-exertional malaise leads, a two-day cardiopulmonary exercise test can document it (Gattoni et al., 2025), and is used only when you can tolerate it.
Endothelial function testing, von Willebrand factor, ADAMTS13, soluble thrombomodulin and vascular inflammation markers. Endothelial damage is a hallmark of COVID-19 and persists in many Long COVID patients, driving both microvascular and larger-vessel dysfunction. Viral persistence markers (spike and nucleocapsid antibody dynamics, viral RNA in blood and stool) are added where the history points to them.
The post-COVID work-up is completed over one to two days at the start of the stay, so that the treatment plan can be written early and the treatment weeks used in full. After your first message the International Office requests the records you have before the video consultation: discharge letters, laboratory results, imaging reports, your medication list and a short timeline. Incomplete records are fine; once the International Office has requested them, a physician reads them before the call and tells you which tests are still needed.
For patients from abroad the work-up is the first step of the Long COVID and ME/CFS apheresis program, a two to three week inpatient stay with a video consultation in English before you travel. The ME/CFS diagnosis page describes how the criteria for ME/CFS are applied when the picture points that way.
Review of your COVID history, symptom timeline, prior treatments and current functional status. Standardized symptom scores record the severity and are repeated later to follow the course.
Blood draw on the first morning for the full panel: microcirculation markers, immune profiling, coagulation analysis, metabolic assessment and inflammatory markers.
Microcirculation assessment, autonomic function testing and any organ-specific evaluation your symptom profile calls for, spread over the day with rest between them.
Review of all findings with your treating physician. We explain which mechanisms are active in your case and how they connect to your symptoms.
From the results, a written protocol that names the mechanisms it targets, the therapies chosen, and which values will be measured again, and when.
No single test diagnoses it. Long COVID is diagnosed from the history and by excluding other causes; the work-up then shows which mechanisms are active. Microclot microscopy, endothelial markers, capillaroscopy, autoantibody panels, viral reactivation tests, autonomic testing and mitochondrial markers each measure one part of the picture, and together they decide the treatment plan.
Whatever you have: discharge letters, laboratory results, imaging reports, a list of your medication and a short timeline of your illness. Incomplete records are fine. A physician reads them before the call and tells you which tests are still needed and whether the program fits your situation.
One to two days at the start of the stay. Blood is drawn on the first morning; the functional tests follow over the next day. The results conference with your physician takes place as soon as the laboratory values are in, and the treatment plan is written from it.
The work-up is designed as the first step of the inpatient program, and most patients from abroad combine the two. Whether a diagnostics-only stay is useful in your case is a question for the video consultation; a physician answers it from your records.
Not yet. Microclot detection by fluorescence microscopy and the capillaroscopy of the microcirculation are research-based methods that St. George Hospital uses in its work-up; their diagnostic value is an open scientific question. They are used here next to established laboratory tests, not instead of them.
Overview of the post-COVID treatment program: symptoms, causes and how the hospital combines its therapies.
The treatment protocol in detail: apheresis, immune modulation, oxygen therapies and paced rehabilitation.
Post-COVID fatigue shares mechanisms with ME/CFS. How the hospital diagnoses and treats persistent fatigue.
When the work-up shows microclots and raised inflammatory proteins, apheresis filters them from the plasma; an individual treatment attempt with emerging evidence.
What H.E.L.P. apheresis involves →Functional testing that shows tissue hypoxia guides the HBOT protocol.
What a hyperbaric oxygen session involves →Mitochondrial test results decide whether IHHT belongs in the plan and at what intensity.
What IHHT training involves →The immune panel guides targeted immune modulation after COVID-related dysregulation.
What immune therapy involves →The initial inquiry is free of charge. The International Office reviews your message and your case directly and gets back to you.
Munich Airport (MUC), about 60 minutes by car.
