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Investigations and Referral

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Related information: Clinical case definitions

Investigations are important to identify symptoms that could be caused by an acute or life-threatening complication, and to assess for other underlying conditions and complications.

These recommendations are for healthcare professionals carrying out initial investigations in primary care or community services for people with new or ongoing symptoms four weeks or more after the start of suspected or confirmed acute COVID-19.


Refer people with ongoing symptomatic COVID-19 or suspected post-COVID-19 syndrome urgently to the relevant acute services if they have signs or symptoms that could be caused by an acute or life-threatening complication, including (but not limited to):

  • severe hypoxaemia or oxygen desaturation on exercise
  • signs of severe lung disease
  • cardiac chest pain
  • multisystem inflammatory syndrome (in children).
Refer people with ongoing symptomatic COVID-19 or suspected post-COVID-19 syndrome urgently for psychiatric assessment if they have severe psychiatric symptoms or are at risk of self harm or suicide.

The panel agreed that no one set of investigations and tests would be suitable for everyone because of the wide range of symptoms and severity. Investigations need to be tailored to the person’s signs and symptoms and whether they are being assessed in primary or secondary care. They agreed that blood tests and exercise tolerance tests (if safe and appropriate for the person) would be useful for most people as investigations and baseline measures, and could be carried out in primary care. These were also the tests most commonly reported in the evidence, along with chest X-rays. The panel suggested some blood tests such as a full blood count and kidney, liver and thyroid function tests, that are commonly carried out to help rule out (or confirm and treat) other conditions.

The evidence suggested that not all pathology shows up on a chest X-ray so the panel agreed it should only be used as part of a holistic assessment to decide if referral or further care are needed in people with respiratory symptoms.7


Offer tests and investigations tailored to people’s signs and symptoms to rule out acute or life-threatening complications and find out if symptoms are likely to be caused by ongoing symptomatic COVID-19, post-COVID-19 syndrome or could be a new, unrelated diagnosis.

If another diagnosis unrelated to COVID-19, is suspected, offer investigations and referral in line with relevant national or local guidance.
Offer blood tests which may include a full blood count, kidney and liver function tests, C-reactive protein test, ferritin, B-type natriuretic peptide (BNP) and thyroid function tests.

The panel discussed the usefulness of carrying out a sit-to-stand test but also agreed clinical judgement would be needed because it is not suitable for everyone (for example, people with chest pain or severe fatigue). They agreed skill sharing between services could help with gaps in knowledge and that a protocol should be followed in order to carry a sit-to-stand test out safely. The panel discussed that appropriate protocols could be found in published studies.4,5 They could not recommend any one in particular as their effectiveness had not been reviewed.


If appropriate, offer an exercise tolerance test suited to the person’s ability (for example the 1-minute sit-to-stand test). During the exercise test, record level of breathlessness, heart rate and oxygen saturation. Follow an appropriate protocol to carry out the test safely.


For advice on sharing skills between services to help community services manage these assessments, see the recommendation on sharing skills and training in section 9.

Postural symptoms are common, so the panel agreed that these should be investigated by taking lying and standing blood pressure and heart rate. Advice on carrying this out is available from the Royal College of Physicians’ brief guide on measuring lying and standing blood pressure.6


For people with postural symptoms, for example palpitations or dizziness on standing, carry out lying and standing blood pressure and heart rate recordings (3-minute active stand test, or 10 minutes if you suspect postural tachycardia syndrome, or other forms or autonomic dysfunction).

Offer chest X-ray by 12 weeks after acute COVID-19 if the person has not already had one and they have continuing respiratory symptoms. Chest X-ray appearances alone should not determine the need for referral for further care. Be aware that a plain chest X-ray may not be sufficient to rule out lung disease.

Evidence suggested that many people struggle to adjust to changes in their life, abilities and self-identity and reported feelings of helplessness and isolation. This was also supported by expert testimony which suggested that symptoms of low mood and anxiety are common. The panel agreed that when mental health symptoms are identified during assessment, people need to be referred for support in line with relevant guidance (see: Royal College of Psychiatrists position statement (2019) The role of liaison psychiatry in integrated physical and mental healthcare).7


Follow relevant national or local guidelines on referral for people who have anxiety and mood disorders or other psychiatric symptoms. Consider referral:

  • for psychological therapies if they have common mental health symptoms, such as symptoms of mild anxiety or mild depression, or
  • to a liaison psychiatry service if they have more complex needs (especially if they have a complex physical and mental health presentation).
After ruling out acute or life-threatening complications and alternative diagnoses, consider referring people to an integrated multidisciplinary assessment service (if available) any time from four weeks after the start of acute COVID-19.

The patient experience evidence described how some people were not offered tests and other people were refused a referral by healthcare professionals because they did not have a positive SARS-CoV-2 test result. Many people who had acute COVID-19 were not tested, particularly earlier in the pandemic. The panel were clear that access to services should not be restricted by the need for a positive SARS-CoV-2 test (PCR, antigen or antibody).


Do not exclude people from referral to a multidisciplinary assessment service or for further investigations or specialist input based on the absence of a positive SARS-CoV-2 test (PCR, antigen or antibody).


4.  Ozalevli S, Ozden A, Itil O, Akkoclu A. Comparison of the Sit-to-Stand Test with 6 min walk test in patients with chronic obstructive pulmonary disease. Respir Med. 2007 Feb;101(2):286-93.

5.  Briand J, Behal H, Chenivesse C, Wémeau-Stervinou L, Wallaert B. The 1-minute sit-to-stand test to detect exercise-induced oxygen desaturation in patients with interstitial lung disease. Ther Adv Respir Dis. 2018;12:1753466618793028.

6.  Royal College of Physicians. Measurement of lying and standing blood pressure: A brief guide for clinical staff. [cited 15 Dec 2020]. Available from URL:

7.  Royal College of Psychiatrists. Position statement PS07/19: The role of liaison psychiatry in integrated physical and mental healthcare. [cited 15 Dec 2020]. Available from URL:


Full details of the evidence and the panel's discussion are in: