Long Covid diagnosis

Overview of how to diagnose long covid.


Long Covid diagnosis

An initial medical examination should be done 4 weeks after infection if symptoms persist to rule out organ dysfunction after Covid-19 and other causes of fatigue. If symptoms persist, targeted symptoms-based examinations should be carried out involving respiratory specialists, cardiologists, neurologists, rheumatologists, dermatologists, psychologists or sleep physicians, depending on the symptom.

The primary entry point for the virus is the respiratory tract and the lungs. Many patients complain of shortness of breath not only during acute infection, but also weeks after the initial symptoms have subsided.

The following diagnostic tests are recommended to assess the extent of lung function impairment:

  • body plethysmography
  • diffusing capacity measurement (TLCO)
  • inspiratory force measurement (Pimax)
  • blood gas analysis as well as oxygen saturation measurement
  • polygraphy and peak flow measurement where necessary
  • assessment of breathlessness using the modified Borg scale (0 - 10 points)

The following laboratory diagnostics can be performed if Long Covid is suspected:

  • blood count
  • electrolytes
  • creatinine
  • eGFR
  • uric acid
  • CRP
  • HbA1c
  • Glucose
  • GOT
  • GPT
  • gamma-GT
  • NT-proBNP where appropriate
  • D-dimers
  • Troponin
  • vitamin D3 level
  • iron
  • ferritin
  • differential blood count

The following cardiological diagnostics are recommended for Long Covid:

  • Exercise ECG
  • transthoracic echocardiography
  • long-term ECG
  • measurement of heart rate variability (respiratory sinus arrhythmia)
  • spiroergometry where appropriate

Following internal medical diagnostics are recommended for Long Covid:

  • 12-lead ECG

  • X-ray of the thoracic organs

  • sonography and vascular duplex examinations

  • Thoracic sonography

Post-infectious fatigue symptoms often occur following viral diseases (e.g. Epstein-Barr virus, SARS-CoV-1 virus, Coxsackie viruses). Besides physical and mental exhaustion, patients with fatigue often suffer from the following:

  • Sleep disorders
  • Pain (joints, muscles, neck)
  • Neurological-cognitive disorders (forgetfulness, concentration and attention disorders, brain fog)
  • Autonomic dysfunction
  • Post-load exhaustion

Overall, women are affected more often than men with Long Covid, and younger people (20-50 years) with internal conditions are affected more often than older people. Post-viral fatigue symptoms are often harmless and subside spontaneously within a matter of days or weeks after infection. The persistence of symptoms over several months, especially beyond 6 months, is referred to as chronic fatigue syndrome (CFS). The symptoms and severity of the acute infection have no influence on the development of chronic fatigue.

Various sets of criteria exist for making a diagnosis (e.g. Canadian criteria for the diagnosis of CFS). The Bell score can be used to classify the severity of the disease. Measurement of hand strength and heart rate variability are also important for the diagnosis of CFS.

Serious mental disorders can occur as a direct consequence of a coronavirus infection. We use a variety of health questionnaires in our clinics to systematically diagnose mental comorbidities:

Questionnaire to identify patients with an anxiety disorder:

  • GAD-7 (Generalized Anxiety Disorder)

Questionnaire for the diagnosis of depression

  • PHQ-9 (Patient Health Questionnaire)

Questionnaire for screening trauma

  • ITQ (International Trauma Questionnaire)

Depending on the specific damage to the central or peripheral nervous system, neuro-rehabilitation has the task of diagnosing the underlying organ damage (e.g. by means of electrophysiology, imaging) and objectifying damage and activity limitations (standardised assessments).

Smell or taste samples can be used to determine the degree of an impairment to smell or taste.

Neurocognitive impairment is one of the most common long-term symptoms following Covid-19 infection. These can be analysed using standardised and normed test procedures for brain performance diagnostics (paper and pencil, computer tests, computer-assisted test procedures). Neuropsychological procedures provide information on the following areas of performance:

  • Attention
  • Motor control and coordination
  • Psychomotor speed
  • Executive functions
  • Language
  • Linguistic / non-linguistic memory
  • Visual-spatial and visual-constructive performance
  • Planning, problem solving
  • General performance diagnostics

Neuropsychological diagnostics objectifies and quantifies feared, suspected or already known damage- and disease-related disorders of cerebral organic performance, emotional processing, behavioural regulation and control.

There are other specific assessments that can be used for Long Covid:

  • 6-minute walking test
  • Exercise ECG
  • Hand force measurement
  • Heart rate variability

Long Covid diagnosis

ICD codes for Long

ICD coding for Long Covid associated with preceding Covid infection.

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Long Covid diagnosis


Questionnaire for your patients to self-report possible symptoms of Long Covid.

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