Acute Kidney Injury- Rapid reduction in kidney function over hours to days, as measured by serum urea and creatinine and leading to a failure to maintain fluid, electrolyte and acid-base homeostasis.
Classification
Risk factors
Diagnosis
Management
Intrarenal/Renal- a consequence of structural damage to the kidney, for example, tubules, glomeruli, interstitium, and intrarenal blood vessels. It may result from persistent pre-renal or post-renal causes damaging renal cells
Postrenal- due to acute obstruction of the flow of urine resulting in increased intratubular pressure and decreased GFR
Prerenal- due to reduced perfusion of the kidneys and leading to a decreased glomerular filtration rate (GFR). It is usually reversible with appropriate early treatment
65 years and over
PMHx - AKI, CKD- eGFR < 60mL/min/1.73m2, hepatic disease, heart failure and diabetes
Greater severity of AKI
Sepsis
Hypovolaemia
Complications
delirium
Sepsis is an important cause of morbidity and mortality in AKI
Hyperkalaemia
Electrolyte imbalances e.g. hyperphosphataemia, hyponatraemia, hypermagnesaemia, hypocalcaemia
Metabolic acidosis
Volume overload (peripheral and pulmonary oedema)
Uraemia- Occurs in severe acute kidney injury and requires dialysis.Symptoms include confusion, lethargy, and altered level of consciousness.
Chronic kidney disease and end-stage renal disease
Symptoms or history of urological obstruction or conditions which may lead to obstruction
Neurological or cognitive impairment or disability
Oliguria (urine output less than 0.5mL/kg/hour).
Nephrotoxic drug use within the last week, NSAIDS, ACE inhibitors, ARBs, diuretics
Exposure to iodinated contrast agents within the past week.
cancer and cancer therapy
immunocompromise
Toxins
Suspect
Any symptoms- nausea and vomiting, or diarrhoea, evidence of dehydration. Reduced urinary output or change to urine colour. Confusion, fatigue and drowsiness
Any risk factors
An illness with no clear acute component and any of the following- CKD, or urological disease, signs of multi system disease affecting kidneys and other organs, symptoms of complications of AKI
Confusion, fatigue, and drowsiness.
An acute kidney injury warning stage test result generated from electronic detection systems in a biochemistry laboratory. This flags up changes in creatinine levels suggestive of AKI for the person receiving the result in primary care.
Detect AKI
A rise in serum creatinine of 26 micromol/L or greater within 48 hours.
Be aware that in the absence of a baseline creatinine value, a high serum creatinine level may indicate AKI, even if the rise in creatinine over 48 hours is less than 26 micromol/L (particularly if the person has been unwell for a few days).
A 50% or greater rise in serum creatinine (more than 1.5 times baseline) known or presumed to have occurred within the past 7 days.
A fall in urine output to less than 0.5 mL/kg/hour for more than 6 hours (if it is possible to measure this, for example, if the person has a catheter).
Identify and treat underlying causes- Shock/sepsis, Hypovolaemia, Obtsruction, Urine analysis and Toxins (SHOUT Pathway)
For renal disease by performing urine dipstick testing for blood, protein, leucocytes, nitrites, and glucose
Renal function and serum potassium levels
The stage of acute kidney injury. In primary care the creatinine level will be the readily result available
Assess volume status checking fluid intake and output, CR time, HR &BP, JVP, Signs of dehydration-mucus membrane, skin turgor, change in urination pattern. Signs of peripheral oedema and pulmonary crackles
ABCDE assessment to determine urgency or relevance of hospital admission
Investigations-Bloods, IV Fluids if apt, treat underlying cause, correct any electrolyte imbalance, review and adjust medication, monitor and adjust diet.
Follow up- monitoring and prevention of further episodes- monitor serum creatinine
Referral
If signs of sepsis, shock,- urgent referral to hospital
Consider referral to a nephrologist when estimated glomerular filtration rate (eGFR) is 30 mL/min/1.73 m2or less.
If pyonephrosis (infected and obstructed kidney) is suspected, immediate ultrasound of the urinary tract (within 6 hours) should be performed.
urgent ultrasound (within 24 hours of assessment) for people who have no identified cause for their acute kidney injury or are at risk of urinary tract obstruction.