Spring 2025

Spring 2025 Issue

Acute Kidney Injury in Older Adults
By Mark D. Coggins, PharmD, BCGP, FASCP
Today’s Geriatric Medicine
Vol. 18 No. 2 P. 22

Laying the Groundwork for Sustained Kidney Health and Overall Well-Being in the Long Term

Acute kidney injury (AKI) is a severe condition characterized by a rapid decline in kidney function that occurs over a few hours to days. This decline can have serious and life-threatening consequences for individuals, as it causes the buildup of metabolic waste and disrupts the kidneys’ ability to regulate essential electrolytes, maintain acid-base balance, and regulate fluid levels in the body. AKI is classified based on decreased urine output and elevations in creatinine levels, with the severity of the condition varying from mild impairment to complete kidney failure. Notably, even individuals experiencing only slight declines in renal function face a significantly higher risk of mortality.1

The identification of patients at the highest risk of AKI or those showing signs of AKI is crucial for implementing timely and effective interventions, as early treatment can help minimize further damage and enhance patient outcomes. While AKI can affect individuals of all ages, particular attention should be given to older adults who face a significantly increased risk. This demographic also tends to experience poorer outcomes, including higher mortality rates, longer hospital stays, more cardiovascular complications, and an elevated risk of progressing to chronic kidney disease (CKD), which may eventually lead to the need for dialysis or a kidney transplant.2

The Statistics
AKI is a significant concern in health care, affecting approximately 15% of hospitalized patients, with a staggering 50% to 60% of those admitted to the ICU experiencing this condition.3 The implications of AKI are severe, as the in-hospital mortality rates for affected patients range from 40% to 50%, while the mortality rate for those individuals in the ICU often exceeds 50 percent.4 Furthermore, around 12% to 15% of individuals with AKI progress to end-stage kidney disease, necessitating dialysis.4 Among those who require renal replacement therapy, mortality rates are reported to be between 30% and 70 percent.5 These alarming statistics underscore the critical importance of raising awareness and implementing early intervention strategies in the management of AKI.

Diagnosis
The Kidney Disease: Improving Global Outcomes criteria are widely used to diagnose AKI.6 According to these guidelines, AKI is identified by any of the following criteria:

• an increase in serum creatinine of at least 0.3 mg/dL (26.5 μmol/L) within 48 hours; or

• an increase in serum creatinine to 1.5 times or more than the baseline level over the previous seven days; or

• a urine output of less than 0.5 mL/kg/h sustained for at least six hours.

Categories of AKI
AKI is classified into three main categories based on the specific cause of kidney dysfunction: prerenal, intrinsic (internal), and postrenal. Understanding these classifications is essential for effective diagnosis and treatment of the condition.

Prerenal AKI
Sometimes called prerenal azotemia, prerenal AKI is characterized by reduced blood flow to the kidneys. Prerenal AKI is the most prevalent form of AKI, accounting for up to 60% of cases.7 The condition is often reversible if the underlying cause is identified and treated promptly. Common contributing factors to prerenal AKI include dehydration, which diminishes the fluid available to the kidneys; heart failure, which reduces the heart’s ability to pump blood to the kidneys efficiently; and sepsis, where a systemic inflammatory cascade disrupts renal blood flow. Additionally, certain medications, including NSAIDs, diuretics, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers can lead to prerenal AKI by mechanisms that decrease kidney blood flow, ultimately resulting in a reduced glomerular filtration rate.

Intrinsic AKI
Intrinsic AKI results from direct damage to the internal structures of the kidneys, such as the tubules, glomeruli, interstitium, and blood vessels. Intrinsic AKI constitutes around 40% of AKI cases.7 Various factors contribute to intrinsic AKI, including infections, inflammation, autoimmune disorders, radiocontrast dye, certain medications like NSAIDs, and some chemotherapeutic and antimicrobial drugs.

Postrenal AKI
Postrenal AKI occurs when there is a blockage in the urine flow after it leaves the kidneys. Postrenal AKI is less common than prerenal and intrinsic forms. Conditions that can block urine outflow from the kidneys include kidney stones, urinary tract infections, blood clots, tumors, prostate conditions, and medications such as anticholinergics like diphenhydramine and oxybutynin, which can cause urinary retention and obstruction.

Older Adults and AKI
Older adults face a heightened risk of developing AKI and experiencing adverse outcomes. Increasing age is a significant risk factor as the incidence of AKI doubles with each decade of aging, and typically, people over 80 years old experience one episode of AKI per year.8 The increase in AKI among older adults can be attributed to several factors. One significant factor is the natural decline in renal function that occurs with aging, which decreases the kidneys’ ability to handle stressors like surgery, dehydration, and medication adjustments. Additionally, many older adults live with multiple chronic conditions, such as diabetes, hypertension, heart failure, and CKD, which further increase their susceptibility to AKI.

The complexities of medication management also play a role, as older adults frequently take multiple medications, some of which may adversely affect kidney function. Moreover, the presentation of AKI symptoms in this age group can be subtle, complicating early recognition and intervention. Lastly, frailty, characterized by reduced muscle mass, compromised immune response, and diminished overall renal capacity, can render older individuals even more vulnerable to kidney injury. Together, these factors underscore the need for heightened awareness and proactive management of kidney health in older populations.

Risk Factors for AKI
Recognizing the risk factors for AKI is essential for health care professionals to enable early identification and intervention. Individuals aged over 65 and those with preexisting CKD are at heightened risk. Conditions like COPD can exacerbate systemic inflammation and hypoxia, further increasing susceptibility to AKI.

Other significant risk factors include dehydration, poorly controlled diabetes, and elevated blood sugar levels, all of which can damage the kidneys. Cardiovascular issues, such as heart failure and hypertension, reduce blood flow to the kidneys, while obesity adds stress through increased blood pressure and insulin resistance. Additionally, low blood pressure from hypotension or shock can impair kidney perfusion.

Hyperuricemia—leading to the formation of uric acid crystals—can obstruct kidney blood flow, while urinary or vascular blockages can significantly affect kidney function. Severe infections, particularly sepsis, contribute to systemic inflammation harmful to the kidneys. Certain medications—like antibiotics, NSAIDs, and diuretics—as well as major surgeries, tobacco use, and excessive alcohol consumption also pose risks. Furthermore, chronic liver disease decreases renal blood flow, while anemia reduces kidney oxygen supply. Blood transfusions may also diminish oxygen delivery, risking damage to kidney cells, and specific medical procedures, including kidney biopsies and dialysis, can elevate the likelihood of AKI.

Awareness of these various risk factors, especially in individuals with multiple risk factors, is crucial for preventing AKI.

Clinical Presentation
AKI can present with a wide range of symptoms that depend on the underlying cause, the extent of kidney damage, and any associated health issues. In cases of mild to moderate AKI, patients may be asymptomatic, but oliguria, characterized by a significant reduction in urine output, is a common sign of the condition.

As kidney injury progresses, the accumulation of nitrogen waste and imbalances in electrolytes and acid-base levels can result in various clinical manifestations. These may include changes in urine output—ranging from reduced output to complete cessation—and changes in urine color. Other potential symptoms include edema, shortness of breath, skin rashes, itching, and neurological effects such as drowsiness, fatigue, confusion, and seizures. In severe instances, the condition can escalate to nausea, chest pain, arrhythmias, and even coma.

Treatment
The treatment of AKI involves identifying and addressing the underlying causes while providing supportive therapies to restore and maintain homeostasis. Supportive therapies include adjusting fluid intake according to the patient’s volume status, carefully managing electrolytes, and correcting acid-base imbalances. Reducing the risk of further kidney damage by eliminating nephrotoxic substances and ensuring blood pressure is maintained at optimal levels to enhance kidney perfusion is crucial. In some cases, renal replacement therapy, like dialysis, may be necessary to protect vital kidney functions.

Preventing AKI
Health care providers are urged to implement strategies to prevent AKI and swiftly and proactively identify at-risk individuals. By doing so, they can facilitate timely and effective management interventions that help to safeguard kidney health and overall patient well-being.

Raise Patient Awareness
Increased patient awareness of AKI is vital for enhancing health outcomes through early detection and timely intervention. Many individuals remain unaware of AKI’s symptoms and risk factors, which can lead to delays in diagnosis and treatment. Further symptoms can easily be overlooked. Recognizing personal risk factors such as diabetes, hypertension, and certain medications enables proactive monitoring and preventative measures.

Informed patients can engage more effectively with health care providers, fostering better communication and collaboration regarding kidney health concerns. Recognizing symptoms like decreased urine output, swelling, fatigue, nausea, and loss of appetite can motivate patients to seek medical attention sooner, which is essential to preventing complications. Early management of AKI can reduce the risk of progression to CKD and the need for dialysis, significantly lowering mortality rates associated with this condition.

Various strategies can be employed to boost awareness of AKI. Public health campaigns can educate the community through media, health fairs, and outreach programs. Additionally, providing accessible educational materials can help individuals learn about symptoms, risk factors, and preventative steps. Training health care professionals to actively screen for AKI and emphasize the importance of kidney health is also essential. Targeted outreach efforts can significantly benefit high-risk populations, ensuring the most vulnerable receive the necessary information and support.

Enhance Recognition
Health care providers are urged to implement proactive strategies to prevent AKI by identifying individuals who are at a heightened risk. Recognizing risk factors early on—such as advanced age, sepsis, dehydration, and existing health issues like diabetes and CKD—is crucial. This awareness enables the development of tailored preventive care plans and facilitates the timely detection of patients who may experience AKI.

Improve Fluid Management
Adequate fluid intake is crucial for maintaining kidney health and preventing AKI, particularly in older adults more vulnerable to dehydration due to age-related changes. Patients should be encouraged to drink fluids regularly and monitor their urine output, especially during hot weather or illness. Also, adequate fluid management is critical during surgical procedures to ensure a balanced fluid state and minimize the risk of AKI.

Follow Sick Day Rules
Health care professionals should also educate patients on “sick day rules” which involve temporarily withholding specific medications during acute illnesses that might exacerbate hypotension or contribute to AKI. These medications include angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, angiotensin receptor-neprilysin inhibitors, diuretics (loop, thiazides, and potassium-sparing), direct renin inhibitors, and NSAIDs.9

Symptoms that warrant withholding these medications include the following:

• vomiting or diarrhea leading to significant fluid loss;
• anorexia or nausea that results in considerably decreased fluid intake;
• new lightheadedness, dizziness, or fainting, especially when sitting or standing up;
• significant weight loss (3 kg or approximately 6.5 lbs within two days); and
• decreased urine output.

Medication Review and Management
Regular medication review is important, as medications account for 20% of AKI incidents.10 Providers should assess both prescribed and over-the-counter medicines for potential nephrotoxicity and minimize the use of harmful drugs whenever possible. If nephrotoxic medications must be used, careful monitoring and adjusting to the lowest effective dose is essential since drug-induced renal impairment can often be reversible if detected and addressed early.

Regular Monitoring
Patients considered high-risk should routinely undergo comprehensive kidney function assessments, including monitoring regular blood creatinine levels to evaluate renal performance. These individuals should receive education on recognizing early warning signs of AKI, such as decreased urine output, swelling in the legs, ankles, or face, persistent fatigue that isn’t alleviated by rest, feelings of nausea, and a significant decrease in appetite. Patient awareness of these symptoms can lead to prompt medical intervention, which is essential in preventing further complications.

Manage Comorbid Conditions
Effectively managing comorbid conditions such as hypertension and diabetes is crucial for reducing the risk of kidney damage. This proactive approach helps to maintain overall health and prevent further complications.

Overall, a comprehensive approach that includes identifying and treating risk factors and regular assessments of kidney health will contribute to better outcomes for patients at risk of AKI.

Importance of a Team-Based Approach
A comprehensive, multidisciplinary, team-based approach is essential for effectively managing AKI. This approach integrates the specialized skills and knowledge of diverse health care professionals, such as nephrologists, who focus on kidney diseases; hospitalists, who oversee the overall care during hospitalization; primary care providers, ensuring continuity of care; nurses, who play a key role in patient monitoring and education; pharmacists, who manage medication regimens and potential drug interactions; and social workers, who address psychosocial factors affecting patient recovery.

A multidisciplinary team can achieve several critical objectives by fostering collaboration among these professionals. They can promptly identify risk factors contributing to AKI, such as dehydration or medication effects, facilitating early intervention strategies tailored to individual patient needs. This coordinated approach enables the development of optimized treatment plans incorporating the best available practices, ensuring that each patient receives personalized care.

Moreover, each discipline has an opportunity to provide patient education that can promote patients’ understanding of AKI’s implications and the importance of follow-up care, which significantly enhances patient involvement in their recovery process. Collectively, these efforts can lead to improved long-term outcomes for AKI survivors, particularly in mitigating the risk of progression to CKD. As a result, a multidisciplinary team approach not only addresses immediate health concerns but also lays the groundwork for sustained kidney health and overall well-being in the long term.

— Mark D. Coggins, PharmD, BCGP, FASCP, is a long term care expert and corporate pharmacy consultant for Touchstone-Communities, a leading provider of senior care that includes skilled nursing care, memory care, and rehabilitation for older adults throughout Texas. He’s a past director of the American Society of Consultant Pharmacists and was nationally recognized by the Commission for Certification in Geriatric Pharmacy with the Excellence in Geriatric Pharmacy Practice Award.

References
1. Fortrie G, de Geus HRH, Betjes MGH. The aftermath of acute kidney injury: a narrative review of long-term mortality and renal function. Crit Care. 2019;23(1):24.

2. Coca SG. Acute kidney injury in elderly persons. Am J Kidney Dis. 2010;56(1):122-131.

3. Gameiro J, Marques F, Lopes JA. Long-term consequences of acute kidney injury: a narrative review. Clin Kidney J. 2020;14(3):789-804.

4. Goyal A, Daneshpajouhnejad P, Hashmi MF, Bashir K. Acute kidney injury. In: StatPearls. Treasure Island, FL: StatPearls Publishing; 2023.

5. Tandukar S, Palevsky PM. Continuous renal replacement therapy: who, when, why, and wow. Chest. 2019;155(3):626-638.

6. Pereira M, Rodrigues N, Godinho I, et al. Acute kidney injury in patients with severe sepsis or septic shock: a comparison between the 'Risk, Injury, Failure, Loss of kidney function, End-stage kidney disease' (RIFLE), Acute Kidney Injury Network (AKIN) and Kidney Disease: Improving Global Outcomes (KDIGO) classifications. Clin Kidney J. 2017;10(3):332-340.

7. Gameiro J, Fonseca JA, Outerelo C, Lopes JA. Acute kidney injury: from diagnosis to prevention and treatment strategies. J Clin Med. 2020;9(6):1704.

8. Sawhney S, Bell S, Black C, et al. Harmonization of epidemiology of acute kidney injury and acute kidney disease produces comparable findings across four geographic populations. Kidney Int. 2022;101(6):1271-1281.

9. Watson KE, Dhaliwal K, Robertshaw S, et al. Consensus recommendations for sick day medication guidance for people with diabetes, kidney, or cardiovascular disease: a modified delphi process. Am J Kidney Dis. 2023;81(5):564-574.

10. Patel JB, Sapra A. Nephrotoxic medications. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2025.