Wounds Versus Kidneys

Reconciling the Protein Dilemma

QUESTION: I am a nurse working with patients who have stage 3, 4, or 5 chronic kidney disease. Our goal is to maintain kidney function for as long as possible without dialysis, so we typically instruct patients to follow a low-protein diet. My dilemma is that many patients also have a wound requiring a high-protein diet for healing. How do I handle these two comorbidities that have opposite recommendations?

ANSWER: It is estimated that approximately 37 million adults have chronic kidney disease (CKD)and 1 in 3 Americans are at risk of its development.¹ Chronic kidney disease is the general term to describe a gradual decrease in renal function. Dialysis can replace most of the functions of the kidneys, but it is certainly a treatment patients wish to avoid for as long as possible.

One way to help preserve failing kidneys is medical nutrition therapy (MNT). The typical renal diet prescribed for people with kidney disease who are not on dialysis is a diet lower in protein. In addition, some patients require fluid restrictions and limit their sodium, potassium, phosphorus, and vitamin C intake. The protein limitation presents a conundrum when treating patients with CKD who also have a wound, because wound care recommendations call for increased amounts of protein. It is sometimes challenging to prescribe MNT for this patient population because it requires advanced renal, wound healing, and nutrition knowledge on the part of the care team.

TYPES OF KIDNEY DISEASE

Kidneys play multiple roles, including cleansing the blood of toxins and transforming the waste into urine, maintaining electrolyte balance, maintaining calcium-phosphorus homeostasis, activating vitamin D, managing blood pressure, and producing erythropoietin for aiding in the creation of red blood cells.² Renal disease affects all these functions and can present itself in various forms, including glomerulonephritis, kidney stones (nephrolithiasis), and polycystic kidney disease. These, along with diabetes mellitus and hypertension, are some causes of CKD, although the last two lead the way. Other common kidney diseases include the following:

• Nephrotic syndrome, a combination of symptoms caused by damage to the filtration unit of the kidneys, the glomeruli, characterized by proteinuria^3,4
• Urolithiasis, also known as kidney stones, which refers to stones formed in the urinary tract
• Acute renal failure or acute kidney injury, a decrease in renal function that occurs within a few hours or days.

EFFECT OF KIDNEY DISEASE ON WOUND HEALING

People with kidney disease, particularly CKD, have various skin conditions that may affect skin integrity. This is possibly related to uremic and inflammatory states. Conditions such as uremic pruritus, calcific uremic arteriolopathy, and nephrogenic systemic fibrosis affect skin integrity and severely decrease quality of life.^5,6 People with CKD also may have other risk factors, such as uncontrolled diabetes mellitus, peripheral vascular disease, venous insufficiency, alterations in calcium-phosphorus metabolism, neuropathy, and aging, which impact wound healing.⁷

Although data are lacking on the mechanism of renal impairment and wound healing phenotype, well-designed animal studies establish the relationship. These types of studies are particularly complex because of the involvement of multiple organs and body systems. Kursh et al⁸ showed that the uremic state decreased tensile strength and collagen formation in mice. That study correlated the decreased caloric intake and weight of the uremic mice with delayed or altered healing.

Seth et al⁹ developed a viable model for inducing kidney impairment via nephrectomy. Their findings in mice with diabetes and kidney injury showed decreased reepithelialization and granulation tissue deposition rates compared to controls. Uremia and anemia were induced in the mice. Histologic immunofluorescent analysis demonstrated a decrease in cellular proliferation and angiogenesis and an increase in inflammation.⁹

Xie et al¹⁰ studied mice with diabetes and renal injury. The researchers noted impaired wound healing processes that included a reduction in cell proliferation and angiogenesis.Findings included inflammatory responses, such as increased M1 polarized macrophages, infiltrated neutrophils, oxidative stress, and cellular apoptosis.

ROLE OF MEDICAL NUTRITION THERAPY

Medical nutrition therapy for kidney disease depends on the type of kidney disease and has become more individualized rather than a one-size-fits-all renal diet. The nutrition care plan depends on patient goals and clinical data, such as abnormalities in laboratory test results and physical symptoms. Most patients with kidney disease require blood pressure medication, an anticoagulant, diuretics, erythropoietin-stimulating agents, and vitamin D–calcium supplementation, all of which can affect nutritional intake and status. The care team should include a registered dietitian nutritionist, who can design a nutrition plan to minimize the progression of renal disease, prevent kidney stone formation, normalize bone retention, and maintain biochemical and electrolyte balance.¹¹

A registered dietitian nutritionist can also help advise on transitioning to a more plant-based diet. Whereas the traditional CKD recommendations have focused on high-biological value protein, such as beef and chicken, current research indicates that plant protein is associated with lower production of uremic toxins and lower serum phosphorus levels. Therefore, at a given total protein intake, a higher proportion of dietary protein from plant sources is possibly associated with lower mortality rates in CKD.¹²

PROTEIN RECOMMENDATIONS

Chronic kidney disease presents a difficult challenge because of the protein restriction required to slow the progression of the disease. When it comes to dietary protein intake, the Kidney Disease Outcomes Quality Initiative recommends a limit of 0.55 to 0.6 g/kg of body weight (BW) daily for patients with CKD, or for patients with CKD and diabetes between 0.6 and 0.8 g/kg of BW (Table 1).¹³

The National Pressure Injury Advisory Panel (NPIAP) protein recommendation is 1.25 to 1.5 g/kg BW/day for patients with a pressure injury who are malnourished or at risk of malnutrition.¹⁴ While the NPIAP recommendations are specifically for pressure injuries, their recommendations often are followed for other types of wounds as well.

To understand the dilemma, we must compare the recommendations in grams and everyday terms of ounces of protein. A comparison is shown in Table 2 using a 145-lb patient as an example.^13,14

PERSONALIZING TREATMENT OPTIONS

It is impossible to adhere to both KDOQI and NPIAP recommendations simultaneously. Practitioners often reconcile these conflicting guidelines by selecting a protein number in the middle range. Although this may seem like a solution, it treats neither medical issue effectively.

A better approach is a frank discussion with patients, family members, and responsible parties so they can provide insight into treatment goals, wishes, fears, and plans. It is also necessary to consider the patient’s level of cognition and ability to make medical decisions when deciding how and with whom to have these discussions.

Some patients accept that dialysis is unavoidable and would prefer to heal their wound(s). Other patients are determined to maintain whatever kidney functions remains even if it means their wound healing may be impeded. The only way to know which direction to lean is to explain clearly that the higher protein intake required to build new tissue to heal the wound can induce hyperfiltration in the kidneys and consequently increase excretion of albumin in the urine, which is thought to negatively impact kidney function over the long term.¹⁵ Proper, clear, and detailed documentation of all education and the rationale for the care plan is needed. Documentation should include when and by whom these care decisions were made.

Clinical practice guidelines are not prescriptive; they are recommendations. It is up to the providers to determine how to apply the recommendations for their patients. Patient input is needed because wounds in patients with CKD are a difficult dilemma requiring more than a standard guideline. Treatment requires empathy, finesse, medical judgment, and clinical experience.

PRACTICE POINTS

People with kidney disease often present with a wound—two challenging comorbidities that significantly affect quality of life. In addition to the medical management of both issues, MNT is needed to aid in the preservation of kidney function and tissue building for wound healing. The dilemma is identifying the appropriate MNT prescription because CKD treatment restricts protein while wound repair requires additional protein. No uniform answer will meet every patient’s needs and individual situation.

The clinician must educate, discuss, and carefully determine an acceptable path forward. Perhaps it is to heal the wound first and then focus on the kidneys. Or perhaps it is to maintain kidney function at all costs. If patients are of sound mind, it is their right to know about the options available for treatment and then make the choice they feel is right for them. If not of sound mind, it is necessary to contact the medical proxy. Thorough medical record documentation and communication of the plan with the entire care team are required.

REFERENCES

1. Chronic kidney disease (CKD). National Kidney Foundation. February 15, 2017. Accessed August 14, 2022. https://www.kidney.org/atoz/content/about-chronic-kidney-disease

2. Wilkens KG. Medical nutrition therapy for renal disorders. In: Mahan LK, Raymond JL, eds. Krause’s Food, Nutrition & Diet Therapy. 14th ed. Saunders; 2017:700-728.

3. Nephrotic syndrome. Mayo Clinic. 2018. Accessed August 14, 2022. https://www.mayoclinic.org/diseases-conditions/nephrotic-syndrome/symptoms-causes/syc-20375608

4. Nephrotic syndrome in adults. National Institute of Diabetes and Digestive and Kidney Diseases. Accessed August 14, 2022. https://www.niddk.nih.gov/health-information/kidney-disease/nephrotic-syndrome-adults#:~:text=For%20people%20who%20have%20developed%20nephrotic%20syndrome%2C%20limiting

5. Kuypers DR. Skin problems in chronic kidney disease. Nat Clin Pract Nephrol. 2009;5(3):157-170. doi:10.1038/ncpneph1040

6. Maroz N. Impact of renal failure on wounds healing. J Am Coll Clin Wound Spec. 2018;8(1-3):12-13. doi:10.1016/j.jccw.2018.01.004

7. Maroz N, Simman R. Wound healing in patients with impaired kidney function. J Am Coll Clin Wound Spec. 2014;5(1):2-7. doi:10.1016/j.jccw.2014.05.002

8. Kursh ED, Klein L, Schmitt J, Kayal S, Persky L. The effect of uremia on wound tensile strength and collagen formation. J Surg Res. 1977;23(1):37-42. doi:10.1016/0022-4804(77)90188-3

9. Seth AK, De la Garza M, Fang RC, Hong SJ, Galiano RD. Excisional wound healing is delayed in a murine model of chronic kidney disease. PLoS One. 2013;8(3):e59979. doi:10.1371/journal.pone.0059979

10. Xie P, Young MW, Bian H, et al. Renal dysfunction aggravated impaired cutaneous wound healing in diabetic mice. Wound Repair Regen. 2019;27(1):49-58. doi:10.1111/wrr.12682

11. Academy of Nutrition and Dietetics. Nutrition Care Manual^®. http://www.nutritioncaremanual.org [by subscription].

12. Chen X, Wei G, Jalili T, et al. The associations of plant protein intake with all-cause mortality in CKD. Am J Kidney Dis. 2016;67(3):423-430. doi:10.1053/j.ajkd.2015.10.018

13. 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):S1-S107. doi:10.1053/j.ajkd.2020.05.006

14. European Pressure Ulcer Advisory Panel, National Pressure Injury Advisory Panel, Pan Pacific Pressure Injury Alliance. Prevention and Treatment of Pressure Ulcers/Injuries. Haesler E, ed. EPUAP/NPIAP/PPPIA; 2019.

15. Ko GJ, Obi Y, Tortorici AR, Kalantar-Zadeh K. Dietary protein intake and chronic kidney disease. Curr Opin Clin Nutr Metab Care. 2017;20(1):77-85. doi:10.1097/MCO.0000000000000342

Nancy Collins is a wound care certified registered dietitian nutritionist based in Las Vegas, NV. She is well known for her expertise in the complex relationship between malnutrition, body composition, and tissue regeneration. To contact Dr Collins, visit her website at www.drnancycollins.com.

Giovanna Rosario Arroyo, a registered dietitian nutritionist in the state of Washington, is currently focusing on geriatrics and providing nutritional care to veterans in their homes. She has 9 years of experience in cardiac, diabetes, intensive care, gastrointestinal, renal, home care, and long-term care, as well as training in renal, diabetes, and weight management to help patients achieve their nutritional goals.
 

The opinions and statements expressed herein are specific to the respective authors and not necessarily those of Wound Management & Prevention or HMP Global. This article was not subject to the Wound Management & Prevention peer-review process.