DIET THERAPY AND KIDNEY DISEASES: PLANNING NUTRIENT LEVELS IN RENAL FAILURE

DIET THERAPY AND KIDNEY DISEASES: PLANNING NUTRIENT LEVELS IN RENAL FAILURE
The diet in renal failure is planned individually for each patient. It takes into account the symptoms, the blood levels of urea and electrolytes, and the nutritional status. Laboratory studies from time to time determine whether the diet needs to be adjusted for one or more nutrients. The diet may be controlled for some or all of these factors: protein, potassium sodium, phosphorus, and fluids. For patients who are awaiting renal dialysis or who are unable to receive dialysis, the diet is more severely restricted than for patients who are dialyzed at periodic intervals.
Energy
Any breakdown of body tissues releases both nitrogen and potassium to the circulation. In severe renal insufficiency this can lead to dangerous increases in the blood levels. Therefore, it is essential to prevent this by giving 35 to 45 kcal per kg (about 2000 to 3000 kcal daily). Carbohydrates and fats are the principal sources of energy.
Protein
Most frequently protein is restricted to less than 0.5 gm per kg body weight for patients who are not on dialysis. An intake of 40 gm protein is common, but it may be as low as 20 gm. For patients on dialysis a protein intake of 60 to 70 gm is usual. On diets severely restricted in protein the essential amino acids are supplied from milk and eggs. The body can synthesize nonessential amino acids from the excess nitrogenous constituents in the blood.
Potassium
In severe renal failure the serum concentration of potassium is sometimes at dangerously high levels. This can be minimized by giving a diet restricted in potassium; 40 mEq (1560 mg) is often prescribed.
When the urine volume is still adequate, potassium is excreted without too much difficulty and restriction is not necessary. If potassium-losing diuretics are used, additional potassium may be needed to maintain normal serum levels.
Sodium
Restriction of sodium ranging from 500 mg to 2000 mg is ordered if there is edema and hypertension. Some patients are “salt losers.” If they are placed on a sodium-restricted diet they will lose more sodium than they are ingesting, and they will become dehydrated.
Phosphorus
When blood levels of phosphorus are elevated, aluminum hydroxide gel is often prescribed to bind the phosphate in the intestinal tract. A phosphorus-restricted diet (1000 to 1500 mg) may also be ordered.
Minerals and vitamins
The protein-restricted diets do not provide recommended daily allowances of calcium, iron, vitamin В complex, and vitamin D. Supplements of these nutrients should be prescribed.
Fluid
When there is oliguria the fluid intake is restricted to the daily volume in the urine plus about 500 to 700 ml which represents the approximate loss from the skin, lungs, and bowel. For example, a urinary excretion of 250 ml daily would permit a fluid intake of 750 ml. This includes all the water present in foods as well as that in beverages. A 100-gm portion of fruits and vegetables supplies 80 to 90 ml water and 100 ml of milk is equal to 87 ml water.
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GENERAL HEALTH