Managing Acute Kidney Injury on the General Ward

Acute kidney injury (AKI) is a time-sensitive syndrome rather than a single diagnosis. A patient may have a small early rise in serum creatinine, reduced urine output, or both, while the underlying problem ranges from dehydration to sepsis, obstruction, medication toxicity, or glomerular disease. On a general ward, the first task is to recognise the change before it becomes severe.

The educational material associated with the Society of Hospital Medicine’s 2017 meeting placed practical bedside assessment alongside research and quality improvement. The conference learning archive remains useful historical context for hospitalists reviewing how AKI criteria, medication safety, fluid management, and escalation strategies were being applied at the time.

For Australian clinicians, the principles are familiar but the setting adds practical detail. A patient transferred between a rural hospital and a tertiary service in Sydney, Melbourne, Brisbane, Perth, Adelaide, or another capital may arrive with incomplete fluid records, while hot weather, gastroenteritis, outdoor work, and long travel can amplify volume loss. Clear criteria help teams act consistently across those circumstances.

What Counts As Acute Kidney Injury

The internationally accepted KDIGO definition identifies AKI when any of three findings is present: a serum creatinine rise of at least 26.5 micromol/L within 48 hours, a rise to at least 1.5 times the known or presumed baseline within seven days, or urine output below 0.5 mL/kg/hour for six hours. These criteria are designed to detect a dynamic decline in kidney function, not just an abnormal single result.

A normal creatinine does not exclude early injury. Muscle mass, age, nutritional state, amputation, and chronic illness influence the baseline concentration. A frail older person may lose substantial filtration before creatinine appears markedly elevated. Conversely, a larger patient with high muscle mass may have a higher baseline without acute disease.

Baseline results should be actively sought through previous hospital records, general practice correspondence, pathology databases, and the patient’s medication history. In Australia, electronic information may be distributed across state systems, private pathology providers, My Health Record, and paper documents from a rural facility. The date and clinical context of the comparison result matter as much as the number itself.

Finding Deterioration Before Creatinine Peaks

Urine output is an immediate bedside signal. It should be measured rather than estimated, with a clear record of voids, catheter drainage, and relevant fluid losses. Oliguria can result from true renal hypoperfusion, obstruction, severe intrinsic injury, or an inaccurate chart. A sudden fall in output deserves review even if the latest creatinine is unchanged.

The ward review should include blood pressure, postural symptoms, capillary refill, mucous membranes, jugular venous pressure, peripheral oedema, lung findings, weight, and fluid balance. No single sign reliably defines volume status. A patient with sepsis may be vasodilated and oedematous while still having inadequate effective circulating volume; a patient with heart failure may be intravascularly depleted after diuresis.

Trends are more useful than isolated values. Plot creatinine, urea, potassium, bicarbonate, fluid balance, weight, and urine output together. A rising creatinine after a hypotensive episode may represent evolving tubular injury, while a rapid improvement after correction of hypovolaemia supports a haemodynamic component. The distinction may be mixed rather than absolute.

Staging Severity And Risk

KDIGO staging turns the diagnostic change into a risk signal. The stage should be based on the worse of creatinine criteria and urine-output criteria. This avoids underestimating patients whose laboratory results lag behind clinical deterioration.

Stage 3 is a major warning, but stage 1 can also deteriorate quickly in sepsis, cardiac disease, liver failure, or ongoing nephrotoxin exposure. Staging should therefore trigger a clinical response rather than replace clinical judgement. A patient with stage 1 AKI and worsening hypotension may be at greater immediate risk than a stable patient whose creatinine has plateaued at stage 2.

Document the baseline, current stage, likely cause, and monitoring interval in the progress note. This makes handover safer and helps the night team recognise whether a new result represents improvement, persistence, or progression.

Searching For Reversible Causes

The initial differential diagnosis is usually grouped into pre-renal, intrinsic renal, and post-renal causes, although patients often have more than one. Common ward triggers include sepsis, vomiting or diarrhoea, haemorrhage, poor intake, excessive diuresis, urinary obstruction, contrast exposure, and medicines that alter renal perfusion or tubular function.

A medication reconciliation should include prescribed drugs, inpatient charts, over-the-counter products, and complementary medicines. Non-steroidal anti-inflammatory drugs such as ibuprofen are readily available in Australian pharmacies and supermarkets, and patients may not regard them as important medicines. Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, diuretics, and some antimicrobials also require review during acute illness.

Examine for retention and obstruction, particularly in older men, patients with pelvic malignancy, and those with a new fall in urine output. A bladder scan is a low-risk bedside test, followed by renal ultrasound when obstruction, hydronephrosis, or an unclear persistent AKI is suspected. Urinalysis can reveal blood, protein, leukocytes, or casts; heavy proteinuria or an active sediment should prompt consideration of nephritis and early specialist advice.

Treating Fluids Medicines And Electrolytes

Fluid treatment should match the physiology. A patient with hypovolaemia may need a carefully reassessed isotonic crystalloid bolus, while a patient with pulmonary oedema needs fluid restriction, oxygen support, and treatment of congestion rather than more fluid. Each intervention should have a measurable endpoint, such as blood pressure, urine output, capillary refill, symptoms, lung findings, or repeat weight.

Review every drug for renal clearance, nephrotoxicity, and current indication. Doses of antimicrobials, anticoagulants, insulin, opioids, and other medicines may need adjustment as kidney function changes. Temporary withholding of selected medicines can be appropriate during hypotension or significant volume depletion, but the plan should specify when they will be reviewed and restarted.

Urgent attention is required for refractory hyperkalaemia, severe metabolic acidosis, pulmonary oedema, uraemic complications, and persistent oliguria with clinical deterioration. Loop diuretics may manage fluid overload but do not repair kidney injury or reliably prevent progression. Nephrology or critical care consultation should be early when the response to initial treatment is poor or the diagnosis is uncertain.

Applying The Criteria In Australian Hospitals

Australian wards commonly measure creatinine in micromol/L, so the 26.5 micromol/L KDIGO threshold should be visible in local protocols and electronic alerts. A result that looks like a modest numerical change can meet the definition. Pathology reporting may also differ between public and private laboratories, making trend review important when a patient moves between services.

The National Safety and Quality Health Service Standards support medication reconciliation, clinical deterioration processes, and communication at transitions of care. These principles are particularly relevant when a patient is transferred from a regional centre to a metropolitan renal or intensive care service. The receiving team needs the last known baseline, fluid totals, urine output, imaging, cultures, and medicines withheld.

Privacy obligations under the Privacy Act 1988 and rules governing My Health Record mean that information should be accessed and shared for appropriate clinical care, with accurate documentation and secure communication. This is practical rather than bureaucratic: a missing baseline result or an undocumented drug exposure can delay diagnosis, while indiscriminate copying of records can create privacy and safety risks.

The local market also shapes prevention. PBS-listed medicines, private prescriptions, pharmacy advice, and easily purchased analgesics all contribute to the medication history. During Australian heatwaves, patients may arrive after reduced intake, heavy sweating, or prolonged outdoor activity; asking about these everyday exposures is often more informative than asking only whether the patient “felt dehydrated.”

Embedding A Reliable Ward Response

A dependable AKI pathway starts with an alert and ends with a named review. When the creatinine or urine output meets KDIGO criteria, the treating clinician should confirm the result, assess circulation and congestion, check medicines, investigate infection and obstruction, and set a repeat-testing interval. The plan should state who will reassess the patient and what findings require escalation.

Monitoring intensity depends on severity and trajectory. Stable stage 1 injury may need daily laboratory testing and strict intake-output measurement, whereas worsening oliguria, potassium elevation, hypotension, or suspected nephritis requires more frequent review. Discharge planning should include repeat renal function, medication restart instructions, sick-day education where appropriate, and communication with the general practitioner.

For a practical next step, add the KDIGO thresholds and a documented urine-output trigger to the next general-ward handover template, then audit ten recent admissions for baseline creatinine, medication review, fluid assessment, and escalation documentation.