Identifying acute kidney injury in people with acute illness

1.1.1.

Investigate for acute kidney injury, by measuring serum creatinine and comparing with baseline, in adults with acute illness if any of the following are likely or present:

• chronic kidney disease (adults with an estimated glomerular filtration rate [eGFR] less than 60 ml/min/1.73 m² are at particular risk)
• heart failure
• liver disease
• diabetes
• history of acute kidney injury
• oliguria (urine output less than 0.5 ml/kg/hour)
• neurological or cognitive impairment or disability, which may mean limited access to fluids because of reliance on a carer
• hypovolaemia
• use of drugs that can cause or exacerbate kidney injury (such as non-steroidal anti-inflammatory drugs [NSAIDs], aminoglycosides, angiotensin-converting enzyme [ACE] inhibitors, angiotensin II receptor antagonists [ARBs] and diuretics) within the past week, especially if hypovolaemic
• use of iodine-based contrast media within the past week
• symptoms or history of urological obstruction, or conditions that may lead to obstruction
• sepsis
• deteriorating early warning scores
• age 65 years or over. [2013]

1.1.2.

Investigate for acute kidney injury, by measuring serum creatinine and comparing with baseline, in children and young people with acute illness if any of the following are likely or present:

• chronic kidney disease
• heart failure
• liver disease
• history of acute kidney injury
• oliguria (urine output less than 0.5 ml/kg/hour)
• young age, neurological or cognitive impairment or disability, which may mean limited access to fluids because of reliance on a parent or carer
• hypovolaemia
• use of drugs that can cause or exacerbate kidney injury (such as NSAIDs, aminoglycosides, ACE inhibitors, ARBs and diuretics) within the past week, especially if hypovolaemic
• symptoms or history of urological obstruction, or conditions that may lead to obstruction
• sepsis
• a deteriorating paediatric early warning score
• severe diarrhoea (children and young people with bloody diarrhoea are at particular risk)
• symptoms or signs of nephritis (such as oedema or haematuria)
• haematological malignancy
• hypotension. [2013]

Identifying acute kidney injury in people with no obvious acute illness

1.1.3.

Be aware that in adults, children and young people with chronic kidney disease and no obvious acute illness, a rise in serum creatinine may indicate acute kidney injury rather than a worsening of their chronic disease. [2013]

1.1.4.

Ensure that acute kidney injury is considered when an adult, child or young person presents with an illness with no clear acute component and has any of the following:

• chronic kidney disease, especially stage 3B, 4 or 5 as shown in table 1, or urological disease
• new onset or significant worsening of urological symptoms
• symptoms suggesting complications of acute kidney injury
• symptoms or signs of a multi-system disease affecting the kidneys and other organ systems (for example, signs or symptoms of acute kidney injury, plus a purpuric rash). [2013]

Table 1

The stages of chronic kidney disease.

Assessing risk factors in adults having iodine-based contrast media

1.1.5.

Discuss the benefits and risks of tests or treatments that use iodine-based contrast media with the person, and their family members and carers if appropriate. Follow the recommendations in the NICE guideline on shared decision making. [2024]

1.1.6.

Be aware that there is a small but increased risk of acute kidney injury associated with an eGFR less than 30 ml/min/1.73 m². [2024]

Assessing risk factors in adults having surgery

1.1.13.

Assess the risk of acute kidney injury in adults before surgery. Be aware that increased risk is associated with:

• emergency surgery, especially when the person has sepsis or hypovolaemia
• intraperitoneal surgery
• chronic kidney disease (adults with an eGFR less than 60 ml/min/1.73 m² are at particular risk)
• diabetes
• heart failure
• age 65 years or over
• liver disease
• use of drugs that can cause or exacerbate kidney injury in the perioperative period (in particular, NSAIDs after surgery).
  Use the risk assessment to inform a clinical management plan. [2013]

1.1.14.

Include the risks of developing acute kidney injury in the routine discussion of risks and benefits of surgery. Follow the recommendations in the NICE guideline on shared decision making. [2013]

Ongoing assessment of the condition of people in hospital

1.2.1.

Follow the recommendations in the NICE guideline on acutely ill adults in hospital on the use of track and trigger systems (early warning scores) to identify adults who are at risk of acute kidney injury because their clinical condition is deteriorating or is at risk of deteriorating. [2013]

1.2.2.

When adults are at risk of acute kidney injury, ensure that systems are in place to recognise and respond to oliguria (urine output less than 0.5 ml/kg/hour) if the track and trigger system (early warning score) does not monitor urine output. [2013]

1.2.3.

Consider using a paediatric early warning score to identify children and young people admitted to hospital who are at risk of acute kidney injury because their clinical condition is deteriorating or is at risk of deteriorating.

• Record physiological observations at admission and then according to local protocols for given paediatric early warning scores.
• Increase the frequency of observations if abnormal physiology is detected. [2013]

1.2.4.

If using a paediatric early warning score, use one with multiple-parameter or aggregate weighted scoring systems that allow a graded response and:

• define the parameters to be measured and the frequency of observations
• include a clear and explicit statement of the parameters, cut-off points or scores that should trigger a response. [2013]

1.2.5.

If using a paediatric early warning score, use one with multiple-parameter or aggregate weighted scoring systems that measure:

• heart rate
• respiratory rate
• systolic blood pressure
• level of consciousness
• oxygen saturation
• temperature
• capillary refill time. [2013]

1.2.6.

When children and young people are at risk of acute kidney injury because of risk factors listed in the recommendation in the section on identifying acute kidney injury in people with acute illness:

• measure urine output
• record weight twice daily to determine fluid balance
• measure urea, creatinine and electrolytes
• think about measuring lactate, blood glucose and blood gases. [2013]

Preventing acute kidney injury in adults having iodine-based contrast media

1.2.7.

Encourage oral hydration before and after procedures using intravenous iodine-based contrast media in adults at increased risk of contrast-associated acute kidney injury (see the recommendation on increased risk in the section on assessing risk factors in adults having iodine-based contrast media). [2019]

1.2.8.

For inpatients having iodine-based contrast media, consider intravenous volume expansion with either isotonic sodium bicarbonate or 0.9% sodium chloride if they are at particularly high risk, for example, if:

• they have an eGFR less than 30 ml/min/1.73 m²
• they have had a renal transplant
• a large volume of contrast medium is being used (for example, higher than the standard diagnostic dose or repeat administration within 24 hours)
• intra-arterial administration of contrast medium with first-pass renal exposure is being used.
  For more information on managing intravenous fluid therapy, see the NICE guideline on intravenous fluid therapy in adults in hospital. [2019]

1.2.9.

Consider temporarily stopping ACE inhibitors and ARBs in adults having iodine-based contrast media if they have chronic kidney disease with an eGFR less than 30 ml/min/1.73 m². [2013, amended 2024]

1.2.10.

Discuss the person’s care with a nephrology team before offering iodine-based contrast media to adults on renal replacement therapy, including people with a renal transplant, but do not delay emergency imaging for this. [2019]

Monitoring and preventing deterioration in people with or at high risk of acute kidney injury

1.2.11.

Consider electronic clinical decision support systems (CDSS) to support clinical decision making and prescribing, but ensure they do not replace clinical judgement. [2013]

1.2.12.

When acquiring any new CDSS or systems for electronic prescribing, ensure that any systems considered:

• can interact with laboratory systems
• can recommend drug dosing and frequency
• can store and update data on patient history and characteristics, including age, weight and renal replacement therapy
• can include alerts that are mandatory for the healthcare professional to acknowledge and review. [2013]

1.2.13.

Seek advice from a pharmacist about optimising medicines and drug dosing in adults, children and young people with or at risk of acute kidney injury. [2013]

1.2.14.

Consider temporarily stopping ACE inhibitors and ARBs in adults, children and young people with diarrhoea, vomiting or sepsis until their clinical condition has improved and stabilised. [2013]

Urinalysis

1.4.2.

Perform urine dipstick testing for blood, protein, leucocytes, nitrites and glucose in all people as soon as acute kidney injury is suspected or detected. Document the results and ensure that appropriate action is taken when results are abnormal. [2013]

1.4.3.

Think about a diagnosis of acute nephritis and referral to the nephrology team when an adult, child or young person with no obvious cause of acute kidney injury has urine dipstick results showing haematuria and proteinuria, without urinary tract infection or trauma due to catheterisation. [2013]

Ultrasound

1.4.4.

Do not routinely offer ultrasound of the urinary tract when the cause of the acute kidney injury has been identified. [2013]

1.4.5.

When pyonephrosis (infected and obstructed kidney[s]) is suspected in adults, children and young people with acute kidney injury, offer immediate ultrasound of the urinary tract (to be performed within 6 hours of assessment). [2013]

1.4.6.

When adults, children and young people have no identified cause of their acute kidney injury or are at risk of urinary tract obstruction, offer urgent ultrasound of the urinary tract (to be performed within 24 hours of assessment). [2013]

Relieving urological obstruction

1.5.1.

Refer all adults, children and young people with upper tract urological obstruction to a urologist. Refer immediately when one or more of the following is present:

• pyonephrosis
• an obstructed solitary kidney
• bilateral upper urinary tract obstruction
• complications of acute kidney injury caused by urological obstruction. [2013]

1.5.2.

When nephrostomy or stenting is used to treat upper tract urological obstruction in adults, children and young people with acute kidney injury, carry it out as soon as possible and within 12 hours of diagnosis. [2013]

Pharmacological management

1.5.3.

Do not routinely offer loop diuretics to treat acute kidney injury. [2013]

1.5.4.

Consider loop diuretics for treating fluid overload or oedema while:

• an adult, child or young person is awaiting renal replacement therapy or
• renal function is recovering in an adult, child or young person not receiving renal replacement therapy. [2013]

1.5.5.

Do not offer low-dose dopamine to treat acute kidney injury. [2013]

Referring for renal replacement therapy

1.5.6.

Discuss any potential indications for renal replacement therapy with a nephrologist, paediatric nephrologist and/or critical care specialist immediately to ensure that the therapy is started as soon as needed. [2013]

1.5.7.

When an adult, child or young person has significant comorbidities, discuss with them and/or their parent or carer and within the multidisciplinary team whether renal replacement therapy would offer benefit. Follow the recommendations in the NICE guideline on shared decision making. [2013]

1.5.8.

Refer adults, children and young people immediately for renal replacement therapy if any of the following are not responding to medical management:

• hyperkalaemia
• metabolic acidosis
• symptoms or complications of uraemia (for example, pericarditis or encephalopathy)
• fluid overload
• pulmonary oedema. [2013]

1.5.9.

Base the decision to start renal replacement therapy on the condition of the adult, child or young person as a whole and not on an isolated urea, creatinine or potassium value. [2013]

1.5.10.

When there are indications for renal replacement therapy, the nephrologist and/or critical care specialist should discuss the treatment with the adult, child or young person and/or their parent or carer as soon as possible and before starting treatment. Follow the recommendations in the NICE guideline on shared decision making. [2013]

Referring to nephrology

1.5.11.

Refer adults, children and young people with acute kidney injury to a nephrologist, paediatric nephrologist or critical care specialist immediately if they meet criteria for renal replacement therapy in recommendation 1.5.8. [2013]

1.5.12.

Do not refer adults, children or young people to a nephrologist or paediatric nephrologist when there is a clear cause for acute kidney injury and the condition is responding promptly to medical management, unless they have a renal transplant. [2013]

1.5.13.

Consider discussing management with a nephrologist or paediatric nephrologist when an adult, child or young person with severe illness might benefit from treatment, but there is uncertainty as to whether they are nearing the end of their life. [2013]

1.5.14.

Refer adults, children and young people in intensive care to a nephrology team when there is uncertainty about the cause of acute kidney injury or when specialist management of kidney injury might be needed. [2013]

1.5.15.

Discuss the management of acute kidney injury with a nephrologist or paediatric nephrologist as soon as possible and within 24 hours of detection when one or more of the following is present:

• a possible diagnosis that may need specialist treatment (for example, vasculitis, glomerulonephritis, tubulointerstitial nephritis or myeloma)
• acute kidney injury with no clear cause
• inadequate response to treatment
• complications associated with acute kidney injury
• stage 3 acute kidney injury (according to (p)RIFLE, AKIN or KDIGO criteria)
• a renal transplant
• chronic kidney disease stage 4 or 5 as shown in table 1. [2013]

1.5.16.

Monitor serum creatinine after an episode of acute kidney injury. Base the frequency of monitoring on the stability and degree of renal function at the time of discharge. Consider referral to a nephrologist or paediatric nephrologist when eGFR is 30 ml/min/1.73 m² or less in adults, children and young people who have recovered from an acute kidney injury. [2013]

1.5.17.

Consider referral to a paediatric nephrologist for children and young people who have recovered from an episode of acute kidney injury but have hypertension, impaired renal function or 1+ or greater proteinuria on dipstick testing of an early morning urine sample. [2013]

1. Risk factor-based screening tool for adults having iodine-based contrast media

What validated risk assessment tools could be used to predict the occurrence of contrast-associated acute kidney injury following the administration of intravenous iodine-based contrast media? [2024]

2. Risk stratification for contrast-induced acute kidney injury

Can risk of contrast-induced acute kidney injury be stratified by eGFR thresholds? [2019]

3. Different oral fluids and oral fluid regimens

What is the relative effectiveness and cost effectiveness of different oral fluids and different oral fluid regimens, both with and without oral N-acetylcysteine, at preventing contrast-induced acute kidney injury? [2019]

4. Long-term outcomes of acute kidney injury

What are the long-term outcomes of acute kidney injury in adults, children and young people? [2013]

5. Rapid referral to nephrology services for moderate to severe acute kidney injury

What is the clinical and cost effectiveness of rapid referral (within 12 hours) to nephrology services for adults with moderate to severe (stage 2 to 3) acute kidney injury not needing critical care? [2013]

6. Definition of acute kidney injury – system for staging and detection

Can a simplified definition and staging system, based on Système International (SI) units, be used to predict short- to medium-term outcomes in acute kidney injury? [2013]

7. Introducing renal replacement therapy

What is the clinical and cost effectiveness of early versus later introduction of renal replacement therapy in patients with acute kidney injury stages 2 and 3, when there is no urgent need for therapy? [2013]

8. Preventing deterioration

What is the clinical and cost effectiveness of continuing ACE inhibitor or ARB treatment, versus stopping treatment 24 hours before cardiac surgery and resuming 24 hours after, in people with chronic kidney disease and an eGFR of less than 30 ml/min/1.73m²? [2013]

Why the committee made the recommendations

The evidence for the accuracy of risk assessment tools or questionnaires to predict an acute kidney injury after administration of iodine-based contrast media was lacking in both quantity and quality. The majority of the risk prediction tools were included in a small number of studies, with low numbers of participants and a younger population than would usually be seen in practice, so limiting the certainty of their accuracy. Therefore, the committee made recommendations based on their knowledge and expertise. They also made a recommendation for research on what validated risk assessment tools should be used to predict contrast-associated acute kidney injury following intravenous iodine-based contrast media.

The evidence for the prognostic accuracy of estimated glomerular filtration rate (eGFR) for iodine-based contrast media-associated acute kidney injury showed that a lower eGFR is associated with an increased risk of acute kidney injury. No evidence was found comparing an eGFR threshold of 30 ml/min/1.73 m² with the currently recommended threshold of 40 ml/min/1.73 m². However, the committee agreed that an increased risk is associated with an eGFR less than 30 ml/min/1.73 m², and this is currently used to indicate poor kidney function.

In current practice, a person is required to have an eGFR test in the 3 months before undergoing contrast media CT scanning. This often results in delayed scans and increases the burden on patients and clinicians to conduct blood tests that may not be needed. In non-emergency settings, the committee agreed that if an eGFR test from within the past 6 months is available, this should be used to support decisions on contrast media scans. Using an eGFR from the previous 6 months as a reference would be an acceptable reflection of a person’s eGFR at the time of iodine-based contrast media use if the person had been clinically stable since the last test. If a recent eGFR is not available, screening questions could be used to assess risk. By including initial questions on pre-existing kidney disease, a large proportion of people would not need blood tests. This is a simple assessment, and if the responses indicate a history of kidney disease, this should prompt clinicians to consider requesting an eGFR test.

The committee noted that people known to have kidney disease would usually have an eGFR result from the past 6 months, because people with a long-term chronic illness are more likely to have regular blood tests to monitor their condition. If a person is acutely unwell at the time of contrast use, an up-to-date blood test would be expected as part of normal practice.

In life-threatening or emergency situations, risk prediction tools should not be applied, and iodine-based contrast media should be administered without delay, if the risk of delaying is likely to be clinically significant.

How the recommendations might affect practice

The recommendations in this update are likely to reduce the volume of eGFR testing, with a set of screening questions removing the need for an eGFR test in people who have a low risk of kidney disease. The recommendation to use an eGFR value from the past 6 months will further reduce the need for testing, resulting in fewer scans being cancelled at short notice.

The committee noted that in practice, clinicians currently use a threshold of 30 ml/min/1.73 m², despite NICE having recommended 40 ml/min/1.73 m². Therefore, the new threshold of 30 ml/min/1.73 m² is not expected to cause a significant change in practice and may further reduce the need for scan cancellations where clinicians had previously followed NICE guidance. Because only people with the greatest risk would need an eGFR test, this new threshold would be cost saving to the NHS because of the reduction in eGFR testing.

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Why the committee made the recommendations

For adults undergoing procedures with intravenous iodine-based contrast media, the evidence showed that oral fluids were as good as intravenous fluids at preventing contrast-induced acute kidney injury. The evidence did not show that any particular type of oral or intravenous fluids is most effective.

The committee agreed that intravenous fluids are not necessary for outpatients who are usually at a lower risk of contrast-induced acute kidney injury. It also agreed that only inpatients at particularly high risk needed intravenous fluids. Most of the risk factors were agreed when the 2013 version of the guideline was developed – apart from the level of eGFR, which was based on the committee’s clinical knowledge and experience in the 2019 update of this section. The committee also agreed that, based on their experience and expertise, the risk for intra-arterial administration depends on the site of the injection, and is particularly high with first-pass renal exposure because the contrast medium passes into the kidneys relatively undiluted.

For inpatients at particularly high risk of contrast-induced acute kidney injury, economic modelling showed that intravenous volume expansion with a regimen containing intravenous sodium chloride 0.9% and/or intravenous sodium bicarbonate provides best value.

Based on the evidence, the committee decided that intravenous volume expansion should be used only for inpatients at particularly high risk and that oral hydration should be encouraged in all other adults at increased risk of contrast-induced acute kidney injury.

The committee agreed that more research on estimating the risk of contrast-induced acute kidney injury would help to inform future guidance, so made a recommendation for research on the use of eGFR thresholds to stratify risk.

Although the committee agreed that oral hydration regimens were non-inferior to intravenous hydration regimens at preventing contrast-induced acute kidney injury, there was not enough comparative data to enable them to be clear about which oral fluid (if any) was most effective. There was some limited evidence that N-acetylcysteine was not beneficial. However, the committee agreed that, in the absence of evidence of harm, this was not sufficient to make a recommendation to restrict its use. Therefore, it made a recommendation for research on different oral fluids and different oral fluid regimens, with and without N-acetylcysteine.

The committee did not consider it necessary for all patients being offered iodine-based contrast media to be routinely discussed with a nephrology team, but concluded that this was important for adults on renal replacement therapy, including people with a kidney transplant. The radiology team responsible for administering the contrast medium or the healthcare professional offering the procedure, such as a cardiologist, would usually do this. For people with other contraindications to intravenous fluids, the committee agreed that the decision to give iodine-based contrast media was better made by individual healthcare professionals.

How the recommendations might affect practice

The recommendations may result in lower resource use for outpatient procedures because people will not need to be admitted to hospital to be given intravenous fluids for volume expansion before they are given a contrast medium.

The recommendation on intravenous volume expansion reflects current practice so there should be no change in practice for inpatients who are at particularly high risk of contrast-induced acute kidney injury. There may be reduced resource use for lower risk inpatients who will not need intravenous fluids.

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