# 005 Etiology of Acute Kidney Injury (AKI) in Hospitalized Geriatric Patients
Authors: Christopher J Anderson, Edmund Duthie MD, Brahm Vasudev MD, Bambi Wessel
To recognize common etiologies of AKI in hospitalized geriatric patients
To review the RIFLE criteria for staging severity of AKI
Context: Geriatric patient in a hospital or other healthcare facility
Action: Response to an increasing serum creatinine or decreasing urine output in a geriatric inpatient
Incidence/Prevalence: Acute kidney injury (AKI), as defined by the precipitous decline in glomerular filtration rate (GFR), is frequently encountered in the elderly patient. The decreased renal reserve and the associated co-morbid conditions of elderly patients (e.g., hypertension, diabetes, heart failure, vascular disease) increase the risk for the development of AKI.
AKI in the geriatric population has been estimated to be somewhere between 1.5% and 7.0% using Medicare billing codes over the last 30 years.
The RIFLE criteria can aid in accurate staging of patients with AKI. This system includes 3 levels of renal dysfunction (R-risk, I-injury, F-failure; have higher sensitivity) and 2 levels of clinical outcomes (L-loss, E-ESRD; have higher specificity).
Underlying Science: Age-dependent structural and functional alterations lead to a significant decrease in renal mass, number of functioning nephrons, and baseline kidney function. Disturbance of auto regulatory defense mechanisms that would normally preserve GFR and renal blood flow can, in the senescent kidney, lead to ischemia and AKI.
The geriatric population may be more vulnerable to ischemic damage because cellular antioxidant defenses decline with age. This suggests the elderly patient may be more susceptible to AKI due to decreased functional renal reserve, attenuated hemodynamic auto regulation, and decreased antioxidant defenses.
Assessment: Etiologies of AKI
Decreased renal perfusion-The elderly may be more susceptible to AKI in a low perfusion state because of attenuated responses to vasodilators and an increase in response to vasoconstrictors. Volume depletion, hypotension, and congestive heart failure (CHF) are causes of perfusion related AKI.
Sepsis-Increasing evidence suggests that sepsis-associated AKI is an inflammatory event. Serum interleukin-6 levels may predict incidence of AKI, as well as severity and mortality among patients admitted to the ICU with acute respiratory distress syndrome or community-acquired pneumonia.
Acute Tubular Necrosis (ATN)- Most frequent cause of AKI in elderly patients. Insults leading to ATN include nephrotoxins (radiocontrast, aminoglycosides)pigment-induced (rhabdomyolysis can occur after a fall with a long lie),and ischemia (sepsis, surgery).
Renovascular disease- acute obstruction of the renal vasculature (cholesterol emboli following intravascular surgery, renal artery thrombosis)
Normotensive ischemic AKI- Normally, a decrease in mean arterial pressure results in preservation of the GFR at mean arterial pressures between 80-100 mm Hg. In patients with impaired renal autoregulation, the GFR is not preserved at these pressures resulting in normotensive ischemic damage. Autoregulation is impaired by non steroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, and angiotensin receptor antagonists.
Acute Interstitial Nephritis- Common practice of polypharmacy in the elderly puts this population at increased risk of having an adverse event that damages the kidney. This includes herbal supplements and over the counter prescription medications in addition to prescription medications such as antibiotics (i.e. β lactam-containing antibiotics such as methicillin).
Ureter (Pelvic malignancy, e.g. invasive cervical carcinoma), Bladder (carcinoma)
Prostate (benign prostatic hyperplasia, carcinoma), Urethra (stricture secondary to trauma, pelvic malignancy)
ACGME Competencies: Patient Care, Medical Knowledge, Practice-Based Learning & Improvement
Acute Kidney Injury in the Elderly Clinics in Geriatric Medicine - Volume 25, Issue 3 (August 2009)
Normotensive Ischemic Acute Renal Failure. J. Gary Abuelo, M.D.N Engl J Med 2007;357:797-805
Author Affiliation: Medical College of Wisconsin, Milwaukee, Wisconsin.
Geriatric Fast Facts are edited by the faculty of the Geriatric Education Teams (GETS) program funded by the Reynolds Foundation, Kathryn Denson, MD, Steven Denson, MD, & Edmund Duthie, MD from the Division of Geriatrics, Medical College of Wisconsin, and are published by the Geriatric Fast Facts Website at the Medical College of Wisconsin. For more information write Kathryn Denson, MD. More information, as well as the complete set of Fast Facts, available at www.mcw.edu/Geriatric-Fast-Facts.htm
Copyright/Referencing Information: Users are free to download and distribute Geriatric Fast Facts for educational purposes only. Citation: Christopher J Anderson, Edmund Duthie, MD, Brahm Vasudev, MD, Bambi Wessel - Fast Fact #005 - Etiology of Acute Kidney Injury (AKI) in Hospitalized Geriatric Patients. February 2012, 14
Geriatric Fast Facts, available at www.mcw.edu/Geriatric-Fast-Facts.htm
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