Faculty Bibliography

Traditional dietary guidelines for patients with kidney disease recommend restriction of plant foods due to concerns about hyperkalemia and associated adverse events. Studies conducted over several decades have shown that the basis for these guidelines does not match the evidence. Serum potassium levels can be elevated in patients with reduced kidney function after consumption of foods with potassium-based additives or with highly concentrated potassium content such as juices, dried fruit, or purees. However, plant foods may have certain qualities that may blunt potassium retention including their alkalinizing effects, the lack of bioavailable potassium, and the impact of dietary fiber in organic plant foods on colonic potassium excretion. Furthermore, there are many benefits of plant foods that patients with kidney disease may be missing by excluding them from their diets by recommending the historical low-potassium "renal diet." Revised dietary recommendations for kidney health may encourage patient-centered kidney recipes that revolve around plant foods and do not restrict them.

Immunoglobulin A nephropathy is the most common glomerulonephritis syndrome in the world, yet there is currently no cure. While blood pressure control, renin-angiotensin-aldosterone system inhibition, and immunosuppression may slow disease progression, low-protein diets, defined as a daily dietary protein intake of 0.6 to 0.8 g/kg body weight, may also decrease immune complex deposition and disease severity, as evidenced in animal models. The link between secondary immunoglobulin A nephropathy and celiac disease has also led to the rise of gluten-free diets and zinc supplementation as potential lifestyle modifications to help manage common immunoglobulin A nephropathy symptoms such as proteinuria and hematuria. In addition, case reports and prospective studies suggest that patients with focal segmental glomerulosclerosis, which manifests as steroid-resistant nephrotic syndrome may also benefit from a gluten-free diet. We highlight the example of a gluten-free, plant-dominant low-protein diet (a different type of low-protein diet that addresses both protein quantity and quality) for patients with immunoglobulin A nephropathy or focal segmental glomerulosclerosis.

Low-protein diets (LPDs), usually defined as a daily dietary protein intake of 0.6 to 0.8 g/kg body weight, have been recommended for decades as a safe and effective lifestyle modification to ameliorate inflammatory damage and proteinuria, reduce glomerular hyperfiltration, and improve metabolic acidosis control in patients with chronic kidney disease (CKD). The mechanism for this is largely attributed to altered tubuloglomerular feedback and afferent arteriole contraction leading to decreased glomerular pressure. Additionally, low protein intake reduces urea generation, which can help delay dialysis initiation in advanced CKD. LPDs have different types including plant-dominant LPDs that can exert additional kidney protective effects as a result of dietary protein quality in addition to quantity. In addition, strong clinical evidence shows that a new class of diabetes mellitus medications, the sodium-glucose cotransporter 2 inhibitors, reduces albuminuria and slows the estimated glomerular filtration rate decline in CKD, even in patients without diabetes mellitus, especially if significant proteinuria is present. Given prior studies investigating the effect of LPDs used in conjunction with angiotensin pathway modulators, we argue that LPDs have a synergistic role in disease management and are expected to display additive effects when combined with sodium-glucose cotransporter 2 inhibitor usage or other pharmacologic agents. Even with medical therapy, it is prudent to implement tailored LPDs for different types of CKD.

Popular diets often influence dietary patterns, which have different implications for kidney stone risk. Despite the wide variety of popular diets, some general principles can be gleaned from investigating their potential impact on nephrolithiasis. Plant-based diets, including Dietary Approaches to Stop Hypertension, Mediterranean, flexitarian, and vegetarian diets, may protect against nephrolithiasis when they consist largely of unprocessed plant foods, while carbohydrate-restricted diets (including high-protein diets and the ketogenic diet) may raise kidney stone risk. Patients should be advised to consume a diet rich in whole plants, particularly fruits and vegetables, and minimize their consumption of animal proteins. Accompanying fruits and vegetables that are higher in oxalate content with more water and some dairy intake may also be useful. (We address the oxalate content of fruits and vegetables further below). Calcium consumption is an important component of decreasing the risk of kidney stones, as higher dietary calcium from dairy or nondairy sources is independently associated with lower kidney stone risk. Patients should also be advised to be conscious of fat intake, as fat in the intestinal lumen may complex with calcium and therefore increase urinary oxalate excretion. Finally, patients should avoid consumption of processed foods, which often contain added fructose and high sodium content, two factors that increase kidney stone risk.

The use of peritoneal dialysis (PD) has been associated with improved quality of life, cost-effectiveness, and better outcomes for patients with kidney failure. However, many patients utilizing PD for replacement therapy face numerous nutritional hurdles. As the use of PD continues to increase worldwide, malnutrition has become an increasingly recognized concern for patients undergoing PD. The nephrology community needs to recognize and treat malnutrition to promote optimal nutritional states for our patients. In this review, we discuss several factors that contribute to malnutrition and protein-energy wasting and explore the benefits and limitations of nutritional parameters used to assess protein-calorie malnutrition. We also emphasize updated guidelines on daily caloric, protein, and micronutrient recommendations, as well as their effects on electrolyte homeostasis.

Direct oral anticoagulants (DOACs) have shifted the landscape of anticoagulation over the past decade, becoming a frequently used pharmaceutical agent. The increased use of DOACs for long-term anticoagulation has led to a rise in reported anticoagulant-related adverse reactions, such as anticoagulant-related nephropathy (ARN). The occurrence of ARN is well reported with warfarin; however, there are few cases of ARN reported with DOAC use. We report the case of an elderly man with coronary artery disease and hypertension who was initiated on apixaban for atrial fibrillation three years prior to presentation but developed rapid renal decline over the six months prior to presentation. The estimated glomerular filtration rate (eGFR) had decreased precipitously from 48 mL/min/1.73 m² to 19 mL/min/1.73 m² with a concurrent drop in hemoglobin in the setting of persistent microscopic hematuria. A renal biopsy showed red blood cell casts consistent with glomerular hematuria, despite no crescents or signs of other forms of glomerulonephritis. The patient's renal function ceased to deteriorate and had a 35% recovery (serum creatinine 2.6 mg/dL, eGFR 25 mL/min/1.73 m²) after the discontinuation of apixaban and conversion to rivaroxaban without the use of corticosteroids. The patient reported at follow-up that he discontinued rivaroxaban four days after initiation on his own accord due to extrarenal bleeding. Our case highlights the importance of prompt recognition and treatment of the underreported but potentially significant incidence of ARN with apixaban in a patient with an otherwise unexplained kidney injury.

Direct oral anticoagulants (DOACs) have shifted the landscape of anticoagulation over the past decade, becoming a frequently used pharmaceutical agent. The increased use of DOACs for long-term anticoagulation has led to a rise in reported anticoagulant-related adverse reactions, such as anticoagulant-related nephropathy (ARN). The occurrence of ARN is well reported with warfarin; however, there are few cases of ARN reported with DOAC use. We report the case of an elderly man with coronary artery disease and hypertension who was initiated on apixaban for atrial fibrillation three years prior to presentation but developed rapid renal decline over the six months prior to presentation. The estimated glomerular filtration rate (eGFR) had decreased precipitously from 48 mL/min/1.73 m² to 19 mL/min/1.73 m² with a concurrent drop in hemoglobin in the setting of persistent microscopic hematuria. A renal biopsy showed red blood cell casts consistent with glomerular hematuria, despite no crescents or signs of other forms of glomerulonephritis. The patient's renal function ceased to deteriorate and had a 35% recovery (serum creatinine 2.6 mg/dL, eGFR 25 mL/min/1.73 m²) after the discontinuation of apixaban and conversion to rivaroxaban without the use of corticosteroids. The patient reported at follow-up that he discontinued rivaroxaban four days after initiation on his own accord due to extrarenal bleeding. Our case highlights the importance of prompt recognition and treatment of the underreported but potentially significant incidence of ARN with apixaban in a patient with an otherwise unexplained kidney injury.

Lifestyle medicine interventions that emphasize healthy behavior changes are growing in popularity in U.S. health systems. Safety-net healthcare settings that serve low-income and uninsured populations most at risk for lifestyle-related disease are ideal venues for lifestyle medicine interventions. Patient-reported outcomes are important indicators of the efficacy of lifestyle medicine interventions. Past research on patient-reported outcomes of lifestyle medicine interventions has occurred outside of traditional healthcare care settings. In this study, we aimed to assess patient-reported outcomes on nutrition knowledge, barriers to adopting a plant-based diet, food and beverage consumption, lifestyle behaviors, self-rated health, and quality-of-life of participants in a pilot plant-based lifestyle medicine program in an urban safety-net healthcare system. We surveyed participants at three time points (baseline, 3 months, 6 months) to measure change over time. After 6 months of participation in the program, nutrition knowledge increased by 7.2 percentage points, participants reported an average of 2.4 fewer barriers to adopting a plant-based diet, the score on a modified healthful plant-based diet index increased by 5.3 points, physical activity increased by 0.7 days per week while hours of media consumption declined by 0.7 h per day, and the percentage of participants who reported that their quality of sleep was "good" or "very good" increased by 12.2 percentage points. Our findings demonstrate that a lifestyle medicine intervention in a safety-net healthcare setting can achieve significant improvements in patient-reported outcomes. Key lessons for other lifestyle medicine interventions include using a multidisciplinary team; addressing all pillars of lifestyle medicine; and the ability for patients to improve knowledge, barriers, skills, and behaviors with adequate support.

Food has the potential to cause and exacerbate many lifestyle diseases. Or it can be used to prevent and treat illnesses like primary hypertension, the metabolic syndrome, and insulin resistance. In parallel, there is also a growing body of evidence of the role of diet in the treatment of kidney disease and its ensuing complications. Popular diets for this purpose have included low-carbohydrate diets, including the ketogenic diet, and higher carbohydrate diets like Mediterranean diets and other plant-based dietary patterns. Low-carbohydrate diets have not shown harm in patients with kidney disease and may benefit a select few. Mediterranean diets have an established record of cardioprotective benefits but also may be beneficial for the kidney. Intermittent fasting has benefits for metabolic health, but limited research exists on the risk or benefit for patients with kidney disease. Plant-based diets, especially those that are lower in protein, may slow kidney disease progression, mitigate uremia, and delay dialysis initiation. Although each dietary pattern has its unique pros and cons, most healthful dietary patterns favor the inclusion of whole, unprocessed foods, preferably from plant-based sources. In this perspective, we discuss the risks and benefits of major popular diets to help guide health care professionals in treating patients with kidney disease.