Cath Lab Digest

  Chronic kidney disease (CKD) is a condition in which the kidneys are damaged and cannot filter blood as well as possible. This damage can cause waste to build up in the body and lead to other health problems, including cardiovascular disease (CVD), anemia, and bone disease. CKD affects more than 20 million people (ie, more than 10% of the population) aged 20 years or older in the US.¹ People with early CKD tend not to feel any symptoms. The only ways to detect CKD are through a blood test to estimate kidney function and a urine test to assess kidney damage. Diabetes is a strong risk factor for developing CKD.

  CKD is usually irreversible and progressive; if it is not treated, over time it can lead to kidney failure, also called end-stage renal disease (ESRD). Once detected, CKD can be managed through medication and lifestyle changes to slow down the disease progression and to prevent or delay the onset of kidney failure. However, the only treatment options for kidney failure are dialysis or a kidney transplant.¹ For registered dietitians (RDs), some of the most challenging patients are those with CKD, because the lifestyle modification involves teaching the patient multiple dietary changes. When the same patient also has diabetes and/or a chronic wound, the diet becomes even more complex as a balance between nutritional requirements for each condition is sought. When treating these patients, it quickly becomes evident that what is prescribed for preserving kidney function is often at odds with what is prescribed to enhance wound healing. The question then becomes how to balance the medical nutrition therapy to ensure the best possible outcome for the patient.

Chronic Kidney Disease Classification

  Kidney function is sometimes expressed as the glomerular filtration rate (GFR). Normal GFR is 90–130 mL/minute. Urea is a product from the metabolism of protein. Normal kidneys maintain a blood urea nitrogen (BUN) range of 5–25 mg/dL. When the kidneys begin to fail to eliminate urea in the urine, urea will build up in the blood.

  The five stages of kidney disease are:

    Stage 1—GFR >90 mL/minute, with persistent protein in the urine;

    Stage 2—GFR 60–89 mL/minute, with persistent protein in the urine (mild disease);

    Stage 3—GFR 30–59 mL/minute (moderate disease);

    Stage 4—GFR 15–29 (severe disease);

    Stage 5—GFR <15 or individual is on dialysis (kidney failure).

  Diet intervention often is related to the stage of CKD, so it is important to know the patient’s stage of kidney disease.

Chronic Kidney Disease Diet Modifications

  Although a CKD diet involves general principles, each patient requires an individualized diet prescription based on the stage of the disease and the patient’s weight, symptoms, activity level, other medical problems, and goals. The general diet focuses on limiting fluids; eating a low-protein diet; restricting sodium, potassium, phosphorous, and other electrolytes; and getting enough calories if unintended weight loss is a problem. The expertise of an RD specializing in renal disease is necessary to individualize the diet to each patient’s unique medical situation. General guidelines are described below but should not be utilized as a substitute for professional advice.

  Calories. The number of calories prescribed is aimed at keeping the patient at a healthy weight, typically between 30 and 35 kcals/kg of body weight. Patients with diabetes or obesity may need a different amount of calories.