Recognising Acute Kidney Injury for Student Nurses
Learn how to recognise possible acute kidney injury, monitor urine output and related observations, and identify clinical patterns that may indicate worsening renal function or wider deterioration.
What is acute kidney injury?
Acute kidney injury, often shortened to AKI, describes a sudden decline in kidney function. It may develop over hours or days and is often associated with another illness, reduced circulating volume, obstruction, medication effects or other clinical problems.
Output may fall
Reduced urine output can be an important sign, particularly when it represents a clear change from the patient's usual pattern.
Renal markers may change
Changes in renal blood results may help clinicians recognise and stage AKI alongside the clinical picture.
Look for wider illness
AKI can occur alongside dehydration, infection, hypotension, circulatory compromise or other acute deterioration.
Look for changes over time
A single urine measurement is less useful than understanding the patient's overall output and how this compares with previous hours or days.
Has output decreased?
Review fluid-balance documentation and identify whether urine output is falling compared with the previous pattern.
Has the pattern changed?
Ask whether the patient is passing urine less frequently or reports difficulty passing urine.
What else is happening?
Consider fluid intake, vomiting, diarrhoea, fever, blood pressure, illness severity and other relevant changes.
Fluid balance is a trend
Intake and output documentation can help identify developing changes, but the figures should always be interpreted alongside the patient's clinical condition.
What findings increase concern?
| Finding | What you may notice | Why it matters |
|---|---|---|
| Reduced urine output | Less urine than previously or a clear decline over time. | This may indicate reduced renal perfusion or impaired kidney function. |
| Hypotension | Blood pressure falls from the patient's normal baseline. | Reduced circulation may affect renal perfusion. |
| Tachycardia | Pulse becomes faster than previously. | This may accompany dehydration, circulatory stress or acute illness. |
| Fluid loss | Vomiting, diarrhoea, bleeding or poor fluid intake. | Reduced circulating volume can contribute to kidney injury. |
| Infection or sepsis | Fever, deterioration, altered observations or systemic illness. | Severe infection may affect circulation and kidney function. |
| Confusion or drowsiness | New neurological change alongside wider illness. | This can indicate significant deterioration requiring prompt assessment. |
Assess the whole patient
Airway
Confirm that the airway appears patent and identify any immediate airway concern.
Breathing
Assess respiratory rate, oxygen saturation, respiratory effort and any new breathlessness.
Circulation
Review pulse, blood pressure, perfusion and evidence of fluid loss or reduced circulating volume.
Disability
Assess consciousness and identify new confusion, drowsiness, weakness or reduced responsiveness.
Exposure
Consider temperature, fluid losses, swelling and other relevant signs while maintaining privacy and dignity.
Escalate
Report reduced urine output, significant observation changes or other deterioration according to local procedures.
Why might AKI develop?
AKI can arise through several different mechanisms. Student nurses do not need to determine the exact cause independently, but recognising the clinical context is valuable.
Reduced renal perfusion
Dehydration, blood loss, hypotension or other circulatory problems can reduce blood flow to the kidneys.
Direct renal problems
Acute illness, inflammation, medication effects and other factors may directly affect kidney function.
Urinary outflow problem
Obstruction to urinary drainage can contribute to deterioration in renal function.
Changes may develop gradually
Stable output
Patient is passing urine regularly and observations are close to baseline.
Output falls
Urine output becomes noticeably lower and the patient reports poor fluid intake and vomiting.
Wider deterioration
Pulse has increased, blood pressure is lower and urine output has continued to decline.
Recognise the combined pattern
Falling urine output becomes more concerning when it occurs alongside fluid loss, hypotension, tachycardia, infection or other signs of physiological deterioration.
Putting the findings together
Example
A patient admitted with vomiting has passed substantially less urine during the last several hours than earlier in the day.
Their pulse has increased and their blood pressure has fallen from previous observations. They report feeling weak and thirsty.
The concern is the combined pattern of reduced urine output, ongoing fluid loss and changing circulatory observations.
As a student nurse, recognise the change, continue an appropriate ABCDE assessment within your competence and promptly communicate your findings to the registered nurse or appropriate clinical team.
AKI recognition errors to avoid
- Ignoring falling urine output. A clear change from baseline should be assessed and reported.
- Looking only at urine output. Review circulation, fluid balance and wider deterioration.
- Assuming urine output alone confirms AKI. AKI is assessed using the wider clinical picture and relevant investigations.
- Missing fluid losses. Vomiting, diarrhoea, bleeding and poor intake may be relevant.
- Failing to compare observations over time. Trends are often more informative than single readings.
- Waiting for severe symptoms. Early recognition may allow earlier clinical review.
- Trying to identify the exact cause before escalating. Recognition and communication come first.
Describe the trend clearly
Example escalation
“I'm concerned about Mr Khan. His urine output has fallen noticeably over the last several hours. He has also had repeated vomiting, his pulse has increased and his blood pressure is lower than earlier.”
This communicates the change in urine output, clinical context and associated physiological deterioration.
Recognise → assess → communicate → escalate
Notice reduced output
Identify changes in urine output, fluid balance or wider clinical condition.
Look at the whole patient
Assess circulation, hydration, fluid losses, observations and consciousness within ABCDE.
Report the pattern
Clearly communicate urine-output changes, observation trends and relevant clinical context.
Build your deterioration-recognition skills
Continue developing your ability to recognise physiological change, assess patients systematically and communicate concerns through the NurseNet Clinical Confidence pathway.
Explore Clinical Confidence →