172 55 mg2

Part II Nutrition Assessment, Consequences, and Implications /mL2 to minimize calcium phosphate crystals

from being deposited into soft tissues (13,14). Diet alone does not usually lower the serum phosphorus level; therefore, “phosphate binders” are often prescribed. These medications bind phosphorus from food in the gastrointestinal tract, which causes some of it to be excreted. To be most effective, phos- phate binders should be taken with meals and snacks and should not be taken at the same time as iron sup- plements. Some common phosphate binders include calcium acetate (PhosLo), calcium carbonate (Tums), and sevelamer hydrochloride (Renagel). If calci- um-based phosphate binders are prescribed, the total elemental calcium (from diet and medication) should not exceed 2,000 mg/d. Some clients with serum phosphorus levels greater than 7 mg/dL may use alu- minum hydroxide (Amphojel) for short-term therapy (no more than 2 weeks). Aluminum binders should be used with caution because high levels can be toxic (13).

PTH levels may be assessed to determine whether the older adult has active bone disease. Controlling PTH levels prevents calcium from being withdrawn from the bones. Therapy with an active vitamin D analogue, such as calcitriol (Calcijex), paricalcitol (Zemplar), or doxercalciferol (Hectorol), may be prescribed if the plasma levels of intact PTH are greater than 300 pg/mL (13).

ANEMIA OF CHRONIC KIDNEY DISEASE

Older adults are also at risk for anemia of CKD. Anemia plays a significant role in the incidence of car- diovascular disease, which is the leading cause of death among those on dialysis. The primary cause for the anemia seen in CKD is the decreased production of the hormone erythropoietin (EPO), which is normally pro- duced by the healthy kidney. This hormone signals the body to make red blood cells. As the kidney loses its ability to make this hormone, hemoglobin and hemato- crit levels start to drop, and anemia develops (15). Hemoglobin is the preferred test to assess anemia. The NKF KDOQI recommends a target hemoglobin of 11 to 12 g/dL and a hematocrit of 33% to 36% (14). In addition to measuring hematocrit and hemoglobin, iron studies will also need to be assessed. Adequate iron stores are necessary for EPO to work effectively. Iron studies include ferritin, iron, iron-binding capacity, and transferrin saturation. Adequate iron status is defined as follows (15):

transferrin saturation 30% or lower and ● serum ferritin 500 ng/mL or lower.

●

If the client is iron deficient, the administration of an erythropoietin stimulating agent must be delayed until iron stores are repleted. Most persons requiring dialysis need iron supplementation because iron stores quickly become depleted during erythropoiesis. Iron can be provided in either oral or intravenous preparations. Most people receive intravenous iron preparations, such as iron dextran (INFeD), iron sucrose (Venofer), and iron gluconate (Ferrlecit), administered during dialysis. These medications can also be given as an oral supplement if not on hemodialysis. Effective treatment of anemia in CKD improves survival, decreases mor- bidity, and improves quality of life (15).

NUTRITION CONSIDERATIONS IN EARLY STAGES OF CHRONIC KIDNEY DISEASE

In the initial stages of kidney disease, blood chemis- tries become altered as the BUN and creatinine levels start to rise. As the disease progresses and as waste products accumulate in the bloodstream, symptoms of uremia develop. These symptoms may include altered taste, poor appetite, nausea, vomiting, and weight loss (7,8).

The MDRD project, funded by the National Institutes of Health, was conducted to determine whether MNT would be beneficial in slowing the pro- gression of kidney disease (16). The investigators con- cluded that blood pressure control, protein restriction, and phosphorus restriction can delay kidney disease progression. Although there may be some evidence that protein restriction may delay the progression of renal failure, the risks of such therapy in already protein-de- pleted older adults may outweigh any short-term bene- fits. Preserving lean body mass and preventing malnutrition is the main objective when prescribing protein restrictions in predialysis clients (see Table 12.2 on page 175 for recommendations) (4). If muscle mass declines and signs of malnutrition begin to develop, liberalization is indicated.

As the GFR approaches 15 mL/min and as symp- toms of uremia become uncontrollable with diet and medication, RRT must be initiated. The renal diet is generally more restrictive for those on hemodialysis than for those receiving peritoneal dialysis. This is pri- marily because those on hemodialysis average treat- ment times of 3 to 4 hours, 3 days a week, for a total therapy time of 9 to 12 hours per week. Those on peri- toneal dialysis average 10 to 12 hours of therapy daily, for a total treatment time of 70 to 84 hours per week. Adequate dialysis is a major factor in nutritional status since poor dialysis leads to uremia (7). Dialysis centers routinely assess adequacy of dialysis. The type of