5 Preventing and managing acute complications

5.1 Acute kidney injury (AKI)

Assessing and managing AKI


Be aware that in people with COVID‑19, acute kidney injury (AKI):

  • may be common, but prevalence is uncertain and depends on clinical setting (the Intensive Care National Audit and Research Centre's report on COVID-19 in critical care provides information on people in critical care who need renal replacement therapy for AKI)

  • is associated with an increased risk of dying

  • can develop at any time (before, during or after hospital admission)

  • may be caused by volume depletion (hypovolaemia), haemodynamic changes, viral infection leading directly to kidney tubular injury, thrombotic vascular processes, glomerular pathology or rhabdomyolysis

  • may be associated with haematuria, proteinuria and abnormal serum electrolyte levels (both increased and decreased serum sodium and potassium). [23 March 2021]


Be aware that in people with COVID‑19:

  • maintaining optimal fluid status (euvolaemia) is difficult but critical to reducing the incidence of AKI

  • treatments for COVID‑19 may increase the risk of AKI

  • treatments for pre-existing conditions may increase the risk of AKI

  • fever and increased respiratory rate increase insensible fluid loss. [23 March 2021]

For information on assessing and managing acute kidney injury (AKI), see the NICE guideline on AKI: prevention, detection and management and the NHS England AKI algorithm.

For information on the management of acute life-threatening hyperkalaemia, see NICE's technology appraisal guidance on patiromer and sodium zirconium cyclosilicate for treating hyperkalaemia.

For information on using intravenous fluids, see NICE's guidelines on intravenous fluid therapy in adults in hospital and intravenous fluid therapy in children and young people in hospital.

For information on managing renal replacement therapy for adults who are critically unwell with COVID-19, see the Renal Association's guidelines on renal replacement therapy for critically unwell adults.


5.2 Acute myocardial injury

Diagnosing acute myocardial injury


For people in hospital with COVID-19 with signs or symptoms that suggest acute myocardial injury, measure high sensitivity troponin I (hs‑cTnI) or T (hs‑cTnT) and N‑terminal pro B‑type natriuretic peptide, and do an electrocardiogram (ECG). [23 March 2021]


Use the following test results to help inform a diagnosis:

  • evolving ECG changes suggesting myocardial ischaemia

  • an NT-proBNP level above 400 ng/litre

  • high levels of hs-cTnI or hs-cTnT, particularly levels increasing over time.

    Elevated troponin levels may reflect cardiac inflammatory response to severe COVID-19 rather than acute coronary syndrome. [23 March 2021]

Managing myocardial injury


For all people with COVID-19 and suspected or confirmed acute myocardial injury:

  • monitor in a setting where cardiac or respiratory deterioration can be rapidly identified

  • do continuous ECG monitoring

  • monitor blood pressure, heart rate and fluid balance. [23 March 2021]


For people with a clear diagnosis of myocardial injury:

  • seek specialist cardiology advice on treatment, further tests and imaging

  • follow local treatment protocols. [23 March 2021]


For people with a high clinical suspicion of myocardial injury, but without a clear diagnosis:

  • repeat high sensitivity troponin (hs-cTnI or hs-cTnT) measurements and ECG monitoring daily, because dynamic change may help to monitor the course of the illness and establish a clear diagnosis

  • seek specialist cardiology advice on further investigations such as transthoracic echocardiography and their frequency. [23 March 2021]

See also the management section for recommendations on care planning and recommendations on escalating and de-escalating treatment.

5.3 Venous thromboembolism (VTE) prophylaxis

In hospital


For young people and adults with COVID-19 that is being managed in hospital, assess the risk of bleeding as soon as possible after admission or by the time of the first consultant review. Use a risk assessment tool published by a national UK body, professional network or peer-reviewed journal. (The Department of Health VTE risk assessment tool is commonly used to develop treatment plans.) [23 March 2021, amended 2 September 2021]


Continue management with a standard prophylactic dose of LMWH for a minimum of 7 days, including after discharge.

See recommendation 5.3.13 on LMWH self-administration. [2 September 2021]


Consider a treatment dose of an LMWH for young people and adults with COVID-19 who need low-flow supplemental oxygen and who do not have an increased bleeding risk.

In August 2021, using a treatment dose of a LMWH outside the treatment of confirmed VTE was an off-label use of parenteral anticoagulants. See NICE's information on prescribing medicines. [2 September 2021]


Continue management with a treatment dose of LMWH for 14 days or until discharge, whichever is sooner. Dose reduction may be needed to respond to any changes in a person's clinical circumstances. [2 September 2021]


Only offer an intermediate or treatment dose of an LMWH to young people and adults with COVID-19 who are receiving high-flow supplemental oxygen, CPAP, NIV or invasive mechanical ventilation as part of a clinical trial. [2 September 2021]

For people with COVID-19 who do not need low-flow supplemental oxygen, follow the recommendations in NICE's guideline on VTE in over 16s.


Do not base prophylactic dosing of heparin on levels of D‑dimer. [23 March 2021, amended 2 September 2021]


For people at extremes of body weight or with impaired renal function, consider adjusting the dose of LMWHs in line with the summary of product characteristics and locally agreed protocols. [23 March 2021, amended 2 September 2021]


For people who cannot have LMWHs, use fondaparinux sodium or unfractionated heparin (UFH).

In August 2021, LMWHs and fondaparinux sodium were off-label for people under 18 years. See NICE's information on prescribing medicines. [23 March 2021, amended September 2021]


For people who are already having anticoagulation treatment for another condition when admitted to hospital:

  • continue their current treatment dose of anticoagulant unless contraindicated by a change in clinical circumstances

  • consider switching to an LMWH if their current anticoagulant is not an LMWH and their clinical condition is deteriorating. [23 March 2021, amended September 2021]


If a person's clinical condition changes, assess the risk of VTE, reassess bleeding risk and review VTE prophylaxis. [23 March 2021, amended September 2021]


Organisations should collect and regularly review information on bleeding and other adverse events in people with COVID-19 having treatment or intermediate doses of LMWHs. [23 March 2021, amended September 2021]


Ensure that people who will be completing VTE prophylaxis after discharge are able to use it correctly or have arrangements made for someone to help them. [23 March 2021, amended September 2021]

In hospital-led acute care in the community


For people with COVID-19 managed in hospital-led acute care in the community settings:

  • assess the risks of VTE and bleeding

  • consider pharmacological prophylaxis if the risk of VTE outweighs the risk of bleeding. [23 March 2021]

People with COVID-19 and additional risk factors

For a short explanation of why the panel made these recommendations, see the rationale section on prevention and management of venous thromboembolism (VTE) prophylaxis.

Full details of the evidence and the panel's discussion are in evidence review D: VTE prevention in COVID-19.

Information and support


Offer people the opportunity to take part in ongoing clinical trials on COVID-19. [23 March 2021]