1. Nutrition for Patients with Kidney Disorders Chapter 21

2. Nutrition for Patients with Kidney Disorders Kidneys perform many vital functions. Urinary excretion is the primary method by which the body rids itself of: –Excess water –Nitrogenous wastes –Electrolytes –Sulfates –Organic acids –Toxic substances –Drugs

3. Nutrition for Patients with Kidney Disorders—(cont.) The kidneys help to regulate acid–base balance by secreting hydrogen ions to increase pH and excreting bicarbonate to lower pH. Involved in blood pressure regulation Play an important role in maintaining normal metabolism of calcium and phosphorus Kidney diseases can profoundly impact metabolism, nutritional status, and nutritional requirements.

4. Nephrotic Syndrome A generic term that refers to a kidney disorder characterized by urinary protein losses greater than 3.5 g/day Major symptoms –Proteinuria –Hypoalbuminemia –Hyperlipidemia –Oedema

5. Nephrotic Syndrome—(cont.) Hypoalbuminemia and proteinuria –May lead to protein–calorie malnutrition, anemia, increased risk of infection, vitamin D deficiency, and increased clotting Hyperlipidemia increases the risk of cardiovascular disease and progressive renal damage. Causes of nephrotic syndrome include diabetes, autoimmune diseases (e.g., lupus, IgA nephropathy), infection, and certain chemicals and medications.

6. Nephrotic Syndrome—(cont.) In some cases, treating the underlying disorder corrects nephrotic syndrome. In others cases, especially diabetes, nephrotic syndrome may be the beginning of chronic kidney disease.

7. Nephrotic Syndrome—(cont.) Nutrition therapy –Goals oTo minimize edema, proteinuria, and hyperlipidemia oTo replace nutrients lost in the urine oTo reduce the risk of progressive renal damage and atherosclerosis

8. Nephrotic Syndrome—(cont.) Nutrition therapy—(cont.) –Benefits of minimizing proteinuria oAn increase in serum albumin, a decrease in serum lipid levels, a slower progression of kidney disease, and less edema

9. Nephrotic Syndrome—(cont.) Sodium and fluid –Sodium restriction begins when fluid retention occurs. –For stages 1 to 4 and hemodialysis oOne thousand to 3000 mg/day are recommended. oRange is 2000 to 4000 mg for peritoneal dialysis. –Fluid is unrestricted in stages 1 to 4 with normal urine output. –For people on hemodialysis, fluid allowance equals the volume of any urine produced plus 1000 mL.

10. Nephrotic Syndrome—(cont.) Phosphorus and calcium –As kidney function deteriorates, the conversion of vitamin D to its active form is impaired. –National Kidney Foundation recommends both phosphorus and calcium intake be controlled. –In stages 1 to 4, phosphorus allowance is based on lab values and calcium is limited to 1000 to 1500 mg/day. –Phosphate binders must be taken with all meals and snacks.

11. Chronic Kidney Disease (CKD) A syndrome of progressive kidney damage and loss of function to the point of end stage renal disease Decrease in the number of functioning nephrons overburdens the remaining nephrons, and the kidney’s ability to filter blood deteriorates. Measured by a decrease in glomerular filtration rate (GFR)

12. Chronic Kidney Disease (CKD)—(cont.) The impact on nutrition –Loss of kidney function produces widespread effects. –As urine output decreases, fluid and electrolytes accumulate in the blood, producing symptoms of overhydration such as increased blood pressure, weight gain, edema, shortness of breath, and lung crackles. –Uremic syndrome –Acidosis occurs.

13. Chronic Kidney Disease (CKD)—(cont.) CKD is associated with premature mortality and decreased quality of life. Progresses slowly and may not be apparent until 50% to 70% of function is lost. In stages 1 to 4, medical and nutrition therapy can potentially delay the progression to stage 5.

14. Chronic Kidney Disease (CKD)—(cont.) Modifiable risk factors –Smoking cessation, an increase in physical activity, and controlling blood lipid levels –Stage 5 requires dialysis or kidney transplant for survival. –Diabetes and hypertension are the leading causes of CKD. –Other risk factors include cardiovascular disease and obesity.

15. Chronic Kidney Disease (CKD)—(cont.) The impact on nutrition –Reabsorption of some nutrients is impaired. –GI absorption of some minerals, such as calcium and iron, is impaired. –Impaired synthesis of renin, erythropoietin, and the active form of vitamin D can lead to high blood pressure (renin), anemia (erythropoietin), and bone demineralization (vitamin D). –Accelerated atherosclerosis increases the risk of coronary heart disease, myocardial infarction, and further renal damage (due to increase blood pressure and reduced oxygen and nutrient delivery).

16. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy –Goals oReduce workload on the kidneys oRestore or maintain optimal nutritional status oControl the accumulation of uremic toxins –Diet modifications are made in response to symptoms and laboratory values and require frequent monitoring and adjustment. –Diet is both complex and dynamic.

17. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Protein oAs kidney function declines, the ability to excrete nitrogenous and other wastes also declines. oModification of Diet in Renal Disease (MDRD) study showed that tight control of blood pressure and a restricted protein intake of 0.3 to 0.6 g/kg/day helped delay the progression of kidney disease.

18. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Protein—(cont.) oIn stages 1 to 4, the recommended daily protein intake is 0.6 to 0.75 g/kg. oProtein allowance may be liberalized to maintain appropriate body protein stores or because the severity of restriction is too difficult to follow. oProtein allowance in stage 5 is 50% higher than the RDA to account for the loss of serum proteins and amino acids in the dialysate.

19. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Calories oWhen protein intake is restricted, it is vital to consume adequate calories to spare protein from being used for energy, enabling it to be used for protein synthesis oFor all stages of CKD  Calorie recommendations are 35 kcal/kg for adults younger than 60 years of age.  Thirty to 35 kcal/kg for those who are older

20. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Calories—(cont.) oDuring peritoneal dialysis, a large amount of calories is absorbed daily through the dialysate (approximately 340–680 kcal/day). oCalories from the dialysate impair the natural sense of hunger and generally prevent a fall in blood glucose levels between meals. oIncreased intake of pure sugars and pure fats helps to meet calorie requirements while keeping protein intake low.

21. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Sodium and fluid oIntake is monitored by weight gain. oFor many clients on hemodialysis, fluid restriction is hardest.

22. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Potassium oLoss of kidney function means potassium excretion is impaired, and hyperkalemia is a risk. oHypokalemia is a risk for people who receive continuous ambulatory peritoneal dialysis, take potassium-wasting diuretics, or who experience vomiting or diarrhea. oAt all CKD stages, potassium allowance is based on the individual’s serum potassium levels.

23. Chronic Kidney Disease (CKD)—(cont.) Nutrition therapy—(cont.) –Other vitamins and minerals oSpecially formulated vitamin supplements oDeficiencies of water-soluble vitamins oFat-soluble vitamins A and E have been shown to accumulate in CKD. oClients who are undergoing dialysis may develop a deficiency of zinc. oIV iron for clients receiving hemodialysis

24. Chronic Kidney Disease (CKD)—(cont.) Translating recommendations into meals –Diet for CKD is complex. –“Choice” system, similar to the diabetic exchange system, may be used to help clients implement dietary restrictions. –Individualized meal plan –Selections can be severely limited.

25. Chronic Kidney Disease (CKD)— (cont.) Diabetic kidney disease –Formerly known as diabetic nephropathy –Risk factors for diabetic kidney disease (DKD) oHyperglycemia, hypertension, and altered lipid levels –Nutrition therapy seeks to controls these risks.

26. Nutrition Recommendation Guidelines for Diabetic Kidney Disease Protein: 0.8 g/kg Sodium: 2300 mg/d Lipids: ≤30% calories from fat, <10% calories from saturated fat, 200 mg cholesterol per day Carbohydrates: 50% to 60% of total calories Phosphorus: 1700 mg/day for stages 1 and 2 800 to 1000 mg/day for stages 3 and 4 Potassium: <4000 mg/day for stages 1 and 2 2400 mg/day for stages 3 and 4

27. Chronic Kidney Disease (CKD)—(cont.) Kidney transplantation –A treatment option for people with stage 5 CKD –Immediate postoperative diet is high in protein and calories to promote healing. –Most dietary parameters are removed when the new kidney functions normally. –Lifelong commitment to “healthy” eating is important.

28. Acute Kidney Injury Acute kidney injury (AKI) is the sudden loss of renal function characterized by an acute increase in serum creatinine and decrease in urine output. Can develop over a period of hours or days Can range from mild to severe Causes: shock, severe infection, trauma, medications, and obstruction Primary focus of treatment is to correct the underlying disorder.

29. Acute Kidney Injury—(cont.) Nutrition therapy –It has not been proven that nutrition therapy for AKI promotes recovery of kidney function or improves survival. –Goal is to provide adequate amounts of calories, protein, and other nutrients to prevent or minimize malnutrition. –It is difficult to achieve nutritional goals with oral, enteral, or parenteral nutrition.

30. Acute Kidney Injury—(cont.) Nutrition therapy—(cont.) –One approach is to strictly limit fluid, electrolytes, and protein. –For patients who are malnourished and hypercatabolic, the approach may be to give ample amounts of protein and nutrients and provide dialysis as needed. –Oral, enteral, or parenteral nutrition is given.

31. Kidney Stones Form when insoluble crystals precipitate out of urine Approximately 75% of kidney stones are made of calcium oxalate. Risk factors –Dehydration or low urine volume, urinary tract obstruction, gout, chronic inflammation of the bowel, and intestinal bypass or ostomy surgery High fluid intake dilutes the urine.

32. Kidney Stones—(cont.) Oxalate –Normally only 2% to 15% consumed is absorbed. Calcium –Binds with dietary oxalate in the intestines, forming an insoluble compound that the body cannot absorb Protein –High intakes of animal protein increase urinary excretion of calcium, oxalate, and uric acid and reduce urinary pH. Sodium –A high sodium intake promotes urinary calcium excretion by decreasing calcium reabsorption by the kidneys.

33. Kidney Stones—(cont.) Nutrition therapy –None of the diet recommendations made to prevent kidney stones are effective when used alone.