Renal Nutrition Update Treating metabolic acidosis with nutritional interventions can decrease the risk for kidney disease progression

BY LINDSEY ZIRKER, MS, RD, CSR

Nephrology providers are used to looking at multiple ways to preserve kidney function, such as managing hypertension and blood sugar levels and using medications to reduce proteinuria and ameliorate cardiovascular problems. For many patients, however, kidney function continues to deteriorate and progress to kidney failure. This could be due to modifiable risk factors that clinicians fail to identify and address. Metabolic acidosis is one of them.

Metabolic Acidosis Undertreated

Metabolic acidosis, defined as serum total CO 2 concentration less than 22 mmol/L, is estimated to be present in about 27.6% of those with CKD stage 4 and 46.4% of those with stage 5 CKD.1 Metabolic acidosis is associated with poor outcomes in those with CKD, such as bone demineralization, muscle wasting, hormone imbalance, hyperkalemia, failure to thrive, malnutrition, increased risk of falls or fractures, and increased progression of CKD.2,3 Despite this, it is estimated that only 17% of patients receive treatment for metabolic acidosis.4 There are clear targets and interventions for correcting metabolic acidosis.

that may be more appropriate for some patients or may be used successfully in addition to sodium bicarbonate.

NEAP Reduction Through Diet

Multiple studies show that reducing net endogenous acid production (NEAP) can help to improve or correct metabolic acidosis. 2,5 Dietary components such as phosphorus and protein are acid­forming in the body, whereas potassium, calcium, and magnesium which can deplete the body’s stores. Highly motivated patients can keep electronic food logs that can estimate mineral intake and a diet’s potential renal­acid load. A renal dietitian can review these logs to help the patient make food choices that support a lower acid load as well as adequate alkalizing minerals. In some cases, supplements may be appropriate to ensure adequate nutrition and good food quality of life because magnesium and calcium from plant sources are not as well absorbed.

Multiple Benefits

Research indicates that correcting metabolic acidosis through dietary changes can provide a multitude of benefits: increased insulin sensitivity, improved muscle mass growth, increased protein reserves, slower progression of kidney disease, reduced inflammation, improved lipid profiles and blood pressure, and reduced pill burden from sodium bicarbonate.2,5,7,8

Correcting metabolic acidosis is another tool for providers to help slow the progression of kidney disease. Including dietary changes (and dietitians) as an intervention for metabolic acidosis provides additional benefits that can support the patient’s health on multiple levels. ■

Lindsey Zirker, MS, RD, CSR, is a renal dietitian and Director of Clinical Services for the Kidney Nutrition Institute in Titusville, Florida. She specializes in autoimmune kidney disease and advanced practice medical nutrition therapy for people with kidney disease.

References

1. Kim HJ. Metabolic acidosis in chronic kidney disease: Pathogenesis, clinical consequences, and treatment. Electrolyte Blood Press. 2021;19(2):29-37.

2. Noce A, Marrone G, Wilson Jones G, et al. Nutritional approaches for the management of metabolic acidosis in chronic kidney disease. Nutrients. 2021;13(8):2534.

The KDOQI (Kidney Disease Outcomes Quality Initiative program) guidelines recommend a serum bicarbonate level between 24­26mmol/L.5 Sodium bicarbonate is a common and effective treatment for metabolic acidosis, but there are nutrition interventions are more alkalizing.2 Following a lowprotein diet or a diet richer in plant proteins naturally reduces the amount of phosphorus and protein, thus reducing NEAP. Without careful planning, however, these diets can still be low in potassium, magnesium, and calcium,

While all these approaches may not be the perfect option for every patient, a survey of CKD patients found that 43% of patients felt that they were capable of making lifestyle changes to reduce complications of CKD and 32% of patients indicated that they would be interested in being referred to see a dietitian.6 The dietitian can work with the patient individually to assess the best way to help them make changes.

The key is for the patient to know that they have options to make dietary changes or to see a dietitian to slow the progression of their kidney disease.

3. Mathur V, Reaven NL, Funk SE, et al. Association of metabolic acidosis with fractures, falls, protein-calorie malnutrition and failure to thrive in patients with chronic kidney disease. Clin Kidney J. 2022;15(7):1379-1386.

4. Whitlock RH, Ferguson TW, Komenda P, et al. Metabolic acidosis is undertreated and underdiagnosed: a retrospective cohort study. Nephrol Dial Transplant. Published online ahead of print Nov. 2, 2022.

5. Ikizler TA, Burrowes JD, Byham-Gray LD, et al. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. Am J Kidney Dis. 2020;76(3 Suppl 1):S1S107. [Erratum published in Am J Kidney Dis. 2021 Feb;77(2):308].

6. Jimenez EY, Kelley K, Schofield M, et al. Medical nutrition therapy access in CKD: A cross-sectional survey of patients and providers. Kidney Med. 2020;3(1):31-41.

7. Goraya N, Narayanan M, Wesson DE. Management of metabolic acidosis in chronic kidney disease: Past, present, and future direction. Adv Chronic Kidney Dis. 2022;29(4):416-423.

8. Scialla JJ, Anderson CA. Dietary acid load: a novel nutritional target in chronic kidney disease? Adv Chronic Kidney Dis. 2013;20(2):141-149.

Renal & Urology News will be covering the American Society of Nephrology’s Kidney Week 2023 conference in Philadelphia, PA, November 2-5. Go to www.renalandurologynews.com for daily reports on noteworthy studies.