SPECIAL CONSIDERATIONS FOR CLIENTS WITH RENAL DISEASES
Dietary treatment is intended to slow the buildup of waste in the bloodstream. Decreasing waste in the bloodstream will control symptoms of fluid retention, hyperkalemia, and nausea and vomiting. The goal is to reduce the amount of excretory work demanded of the kidneys while helping them maintain fluid, acid-base, and electrolyte balance. Clients require sufficient protein to prevent malnutrition and muscle wasting. Too much, however, can contribute to uremia. Typically, the client with chronic renal failure will have protein and sodium, and possibly potassium and phosphorus, restricted.
It is essential that renal clients receive sufficient calories—25 to 50 calories per kilogram of body weight—unless they are overweight. Energy requirements should be fulfilled by carbohydrates and fat. The fats must be unsaturated to prevent or check hyperlipidemia. If the energy requirement is not met by carbohydrates and fat, ingested protein or body tissue will be metabolized for energy. Either would increase the work of the kidneys because protein increases the amount of nitrogen waste the kidneys must handle. The diet may limit protein to as little as 40 grams for predialysis clients. The specific amount of protein allowed is calculated according to the client’s glomerularfiltration rate (GFR) and weight.
Fluids and sodium may be limited to prevent edema, hypertension, and congestive heart failure. Calcium supplements may be prescribed. In addition, vitamin D may be added and phosphorus limited to prevent osteomalacia (softening of the bones due to excessive loss of calcium). Phosphorus appears to be retained in clients with kidney disorders, and a disproportionately high ratio of phosphorus to calcium tends to increase calcium loss from bones.
Potassium may be restricted in some clients because hyperkalemia tends to occur in end-stage renal disease (ESRD). Excess potassium can cause cardiac arrest. Because of this danger, renal clients should not use salt substi-tutes or low-sodium milk because the sodium in these products is replaced with potassium. Potassium restriction can be especially difficult for a renal client, who probably must limit sodium intake. Potassium is particularly high infruits—one of the few foods a client on a sodium-restricted diet may eat without concern.
Renal clients often have an increased need for vitamins B, C, and D, and supplements are often given. Vitamin A should not be given because the blood level of vitamin A tends to be elevated in uremia. If a client is receiving antibiotics, a vitamin K supplement may be given. Otherwise, supplements of vitamins E and K are not necessary. Iron is commonly prescribed because anemia frequently develops in renal clients. It is sometimes necessary to increase the amount of simple carbohydrates and unsaturated fats to ensure sufficient calories.
Dialysis is done by either hemodialysis or peritoneal dialysis. The most common is hemodialysis. Hemodialysis requires permanent access to the blood-stream through a fistula. Fistulas are unusual openings between two organs. They are often created near the wrist and connect an artery and a vein. Hemodialysis is done three times a week for approximately 3 to 5 hours each visit (Figure 19-2).
Peritoneal dialysis uses the peritoneal cavity as a semipermeable membrane and is less efficient than hemodialysis. Treatments usually last about 10 to 12 hours a day, three times a week (Figure 19-3). Some clients also use continuous ambulatory peritoneal dialysis (CAPD). The dialysis fluid is exchanged four or five times daily, making this a 24-hour treatment. Clients on CAPD have a more normal lifestyle than do clients on either hemodialysis or peritoneal dialysis. Some complications associated with CAPD include peri-tonitis, hypotension, and weight gain.
Dialysis clients may need additional protein, but the amount must be carefully controlled to prevent the accumulation of protein waste between treatments.
A client on hemodialysis requires 1.0 to 1.2 grams of protein per kilo-gram of body weight to make up for losses during dialysis. A client on peritoneal dialysis will require 1.2 to 1.5 grams of protein per kilogram of body weight. The protein needs for clients on CAPD are 1.2 grams per kilogram of body weight. Seventy-five percent of this protein should be high biological value (HBV) protein, which is found in eggs, meat, fish, poultry, milk, and cheese.
Potassium is usually restricted for dialysis clients. Healthy people ingest from 2,000 to 6,000 mg per day. The daily intake allowed clients in renal failure is 3,000 to 4,000 mg. End-stage renal disease further reduces intake allowed to 1,500 to 2,500 mg a day. The physician will prescribe the milli-grams of potassium needed by the client. Table 19-1 lists low-, medium-, and high-potassium fruits and vegetables.
Clients are taught to regulate their intake by making careful choices. Milk is normally restricted to 1 ⁄2 cup a day because it is high in potassium and high in methionine, an essential amino acid. A typical renal diet could be written as “80-3-3,” which means 80 grams of protein, 3 grams of sodium, and 3 grams of potassium a day. There may be a phosphorus restriction also. And there is often a need for supplements of water-soluble vitamins, vitamin D, calcium, and iron.
The ability of the kidney to handle sodium and water in ESRD must be assessed often. Usually, the diet contains 3 grams of sodium, which is the equivalent of a no-added-salt diet. Sodium and fluid needs may increase with perspiration, vomiting, fever, and diarrhea. The fluid content of foods, other than liquids, is not counted in fluid restriction. Clients on fluid restriction must be taught to measure their fluid intake and urine output, examine their ankles for edema, and weigh themselves regularly.
After kidney transplant, there may be a need for extra protein or for the restric-tion of protein. Carbohydrates and sodium may be restricted. The appropriate amounts of these nutrients will depend largely on the medications given at that time.
Additional calcium and phosphorus may be necessary if there was substantial bone loss before the transplant. There may be an increase in appe-tite after transplants. Fats and simple carbohydrates may be limited to prevent excessive weight gain.
Because the causes of renal stones have not been confirmed, treatment of them may vary. In general, however, large amounts of fluid—at least half of it water—are helpful in diluting the urine, as is a well-balanced diet. Once the stones have been analyzed, specific diet modifications may be indicated.
Calcium Oxalate Stones.About 80% of the renal stones formedcontain calcium oxalate. Recent studies provide no support for the theory that a diet low in calcium can reduce the risk of calcium oxalate renal stones. In fact, higher dietary calcium intake may decrease the incidence of renal stones for most people. Dietary intake of excessive animal protein has been shown to be a risk factor for stone formation in some clients.
Stones containing oxalate are thought to be partially caused by a diet especially rich in oxalate, which is found in beets, wheat bran, chocolate, tea, rhubarb, strawberries, and spinach. Evidence also indicates that deficiencies of pyridoxine, thiamine, and magnesium may contribute to the formation of oxalate renal stones.
Uric Acid Stones.When the stones contain uric acid, purine-richfoods are restricted (Table 19-2). Purines are the end products of nucleopro-tein metabolism and are found in all meats, fish, and poultry. Organ meats, anchovies, sardines, meat extracts, and broths are especially rich sources of them. Uric acid stones are usually associated with gout, GI diseases that cause diarrhea, and malignant disease.
Cystine Stones.Cystine is an amino acid. Cystine stones may formwhen the cystine concentration in the urine becomes excessive because of a hereditary metabolic disorder. The usual practice is to increase fluids and recommend an alkaline-ash diet.
Struvite Stones.Struvite stones are composed of magnesium ammo-nium phosphate. They are sometimes called infection stones because they develop following urinary tract infections caused by certain microorganisms. A low-phosphorus diet is often prescribed.