471 high urine output, and, as a result, sodium sup plementation may be necessary Most infant for mulas and breast milk are low in sodium One study, which used diluted formula to provide adequate flui[.]
26 Nutritional Assessment and Prescription for Children Receiving Maintenance Dialysis high urine output, and, as a result, sodium supplementation may be necessary Most infant formulas and breast milk are low in sodium One study, which used diluted formula to provide adequate fluid for children with polyuria, advised providing 2–4 mEq of sodium supplementation per 100 mL of formula [91] Higher sodium formulas may decrease or eliminate the need for supplementation The DRI for sodium should be met to help prevent neurological damage, poor growth, or blindness during infancy [5, 7] The need for sodium supplementation will often resolve with age and as children begin consuming solid foods Very high or low serum levels of potassium, another key electrolyte, can cause serious cardiac outcomes Most patients with anuria require potassium restriction [5] Data from CKiD indicates that oral potassium intake is actually quite low and very few children exceed recommended intakes [92] This finding can likely be extrapolated to children on dialysis in whom fruit and vegetable consumption is low When hyperkalemia persists, non-dietary causes such as tissue breakdown, protein energy wasting, constipation, or medications (such as ACE inhibitors or ARBs) should also be considered as possible etiologies [93] In small children with renal tubular disorders, potassium allowances may be very limited A guideline of 1–3 mmol/kg or 40–120 mg/kg of potassium has been suggested In the case of a 5-kg infant, the potassium allowance would be only 200–600 mg of potassium daily [5] One approach to reduce potassium intake is by the pre-treatment of feeds with sodium or calcium ion exchange resins There are noted risks with this practice, including alteration of other vitamin and mineral levels, and development of potentially serious biochemical derangements [94, 95] Another option for limiting potassium intake is to use a very low potassium pediatric renal formula, which when combined with a standard formula, decreases potassium load Feeds should be titrated to meet individual potassium needs [7] Potassium restriction is not often indicated for PD patients who are high transporters, and in some cases potassium supplementation is indicated Conversely, a low transporter may need to 471 tightly limit dietary potassium [5, 18, 19] (Table 26.1) Managing bicarbonate levels in CKD is also important Excretion of an acid load is impaired, and the resulting acidosis causes poor growth, elevated potassium levels, increased risk of secondary hyperparathyroidism, and the progression of CKD to ESKD [3, 5, 94, 96] Alkali supplementation in the form of sodium bicarbonate is typically used to increase CO2 levels to above 22 mmol/L as per KDOQI recommendations [5] The use of low chloride formulas may also improve acidosis Bone Mineral Management Chronic kidney disease- mineral and bone disorder (CKD-MBD) is a complication involving abnormalities in calcium, phosphorus, PTH or vitamin D regulation, variation in the bone itself, or extra-skeletal abnormalities such as soft tissue damage [97] Early nutrition intervention is key to addressing this phenomenon [98, 99] Complications due to elevated phosphorus have been shown to present well before the need for dialysis, with bone mineral changes taking place as early as CKD stage [99] Phosphorus is abundant in today’s food supply and easily consumed in excess Western diets, characterized by increased intake of processed and fast foods containing phosphorus-based food additives, pose a challenge to the management of serum phosphate levels [100] Eighty-eight percent of adolescents in one HD unit had elevated serum phosphorus levels despite reporting adherence to dietary guidelines [101] Another study of the typical American diet found additives alone may contribute 1000 mg of phosphorus per day over and above what is naturally found in food [102] In addition to avoiding excess intake of dairy and meats that are naturally high in phosphorus, the primary intervention should be limiting foods processed with inorganic phosphorus Phosphorus from nuts, beans, and other plant proteins may be less well absorbed than previously believed due to their high phytate contents These plant-based sources of phosphorus, which were previously restricted, C L Nelms et al 472 are now recommended as part of a healthful intake [81] It is imperative that the patient receiving dialysis be counseled to limit dietary phosphate intake and take associated phosphate-binding medications [5] (Table 26.7) Excessive phosphate intake leads to an eventual rise in PTH, while a reduction of dietary phosphorus intake helps correct elevated PTH levels The effects of elevated phosphorus levels are dramatic and can include cardiovascular disease, poor transplant outcomes, and severe bone damage Even when PTH and serum phosphorus are controlled with medication, excessive phosphorus intake may cause high levels of FGF-23, an early phosphorus- modulating precursor, and damaging bone and organ effects may be taking place [103, 104] Calcium plays an important role in bone health Unlike adult dialysis patients, children need calcium for optimal bone accrual and should achieve intakes of 100–200% of the DRI for calcium [5, 98] (Table 26.7) Excessive calcium, whether from diet or calcium-based phosphate binders, should be avoided An early study showed that adolescents and young adults consuming calcium-based phosphate binders in excess of the maximum recommended calcium intake had cardiovascular damage and calcification by the mid-20s [105] When hypercalcemia is present, calcium intake should be limited Excess serum phosphorus draws calcium into the bloodstream, making it available for calcification of soft tissue, leading to bone disease and cardiovascular damage [5] Vitamin D is another component of bone mineral management When phosphorus is elevated, PTH increases, and its effectiveness is reduced, in turn reducing serum calcium and active vitamin D. In CKD, activation of vitamin D by the kidney is reduced [106] (see discussion in other chapters in this text) Adequate active vitamin D will help prevent hyperparathyroidism and may reduce the risks of other chronic diseases The ESPN native vitamin D therapy clinical practice guidelines recommend the use of active vitamin D as first-line treatment of secondary hyperparathyroidism [107] Children on dialysis routinely receive active vitamin D (1,25-OH) through oral intake or supplementation Vitamins Serum retinol levels are elevated in as many as 77% of children in CKD stages 2–5 and 94% of pediatric dialysis patients [108–110] Elevated retinol levels are common even when children are not meeting recommended intakes of vitamin A for healthy children KDOQI recommends against supplementation with vitamin A to reduce the long-term risks such as liver damage since vitamin A is not well-cleared through dialysis [5] Recent work has also implicated elevated serum retinol levels in hypercalcemia [109] as Table 26.7 Recommended calcium and phosphorus intake by age in children receiving maintenance dialysis Age 0–6 m 7–12 m 1–3 y 4–8 y 9–18 y Recommended calcium intake (mg/d) Upper limit for CKD DRI (mg/d) stages 2–5, 5Da 210 ≤420 270 ≤540 500 ≤1000 800 ≤1600 1300 ≤2500 Recommended phosphorus intake (mg/d) DRI (mg/d) Normal phosphorus High phosphorus and high and high PTHb PTHc 100 ≤100 ≤80 275 ≤275 ≤220 460 ≤460 ≤370 500 ≤500 ≤400 1250 ≤1250 ≤1000 Adapted from the KDOQI Pediatric Nutrition Guidelines [5], http://www.ihi.org/resources/Pages/OtherWebsites/ InstituteofMedicine.aspx [74], https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/dietary- reference-intakes/tables.html [78], and https://health.gov/dietaryguidelines/2015/guidelines/appendix-7/ [179] a 200% of the DRI to maximum of 2500 mg elemental calcium, from diet and phosphorus binders b ≤100% of the DRI c ≤80% of the DRI 26 Nutritional Assessment and Prescription for Children Receiving Maintenance Dialysis elevated retinol levels promote osteoclastic action and inhibit osteoblastic action in bone If serum calcium levels are high due to an unknown etiology, retinol levels should be assessed Dietary vitamin A content may be difficult to adjust in an oral eater with a mixed diet; however, modifications to formula and enteral feed prescriptions may be warranted as a greater number of formula- fed infants with higher vitamin A intake have higher retinol and calcium levels [109] Multivitamin preparations containing vitamin A are contraindicated to prevent any additional intake of vitamin A beyond normal dietary intake When kidney function is impaired, fat-soluble vitamins E and K are not well-cleared While information on these vitamins specific to pediatric dialysis patients is limited, and there is no indication to regularly evaluate or supplement vitamin K, evidence from the general pediatric population suggests that vitamin K is depleted with excess antibiotic use [111] Given that children receiving dialysis are routinely prescribed antibiotics for treatment of infections (e.g., peritonitis, catheter infections), it is prudent to be aware of side effects (bruising and abnormal coagulation studies) related to inadequate vitamin K. Joyce [110] found vitamin E levels were elevated in 87% of children receiving dialysis Yet, there is also evidence that vitamin E supplementation improves oxidative stress which consequently improves erythropoietin-resistant anemia [112, 113] Concern with serum levels not reflecting clinical and intracellular deficiency adds to the challenge of managing vitamin E [113] There is currently insufficient evidence to recommend vitamin E supplementation Levels of 500–1000 mg of supplemental vitamin C intakes have been shown to increase serum oxalate levels, increasing the risk for kidney stones in adult renal patients [114] However, 100–300 mg vitamin C can be lost during a single dialysis treatment, with plasma levels decreasing about 50% with standard hemodialysis [115] Young children on PD receiving fortified formula with a moderate supplement were shown to maintain positive vitamin C balances [116] Daily supplementation with 250 mg of vitamin C showed improved intima media thickness and 473 cardiovascular status in a small study of children with CKD [117], and another study of dialysis patients demonstrated improved lipid profiles likely related to vitamin C-induced reductions in uric acid [118] While supplemental vitamin C needs for the pediatric dialysis patient remain unclear, excess vitamin C should be avoided To address the vitamin needs of children with CKD, KDOQI recommends a standard water- soluble vitamin supplement be given to dialysis patients due to potential dialysate losses and inadequate dietary intakes While excessive intakes of water-soluble vitamins are unlikely to cause harm, serum levels of B vitamins should be assessed on occasion [5], as some deficiencies, such as riboflavin, folate, and vitamin B12, may contribute to anemia The B vitamin content of select standard supplements may exceed needs, as evidenced by rates of elevated levels in one patient population study [110] Currently, no pediatric-specific renal vitamin supplement is available In practice, reduced doses of adult renal vitamin preparations are used to match age- appropriate needs While vitamin doses may not perfectly align with the varying pediatric goals, supplementation is superior to inadequate water- soluble vitamin intake Patient-specific estimates of vitamin and mineral requirements must take into account factors such as age, oral intake, and frequency of dialysis [5] It is suspected that PD transport status also affects vitamin and mineral needs [110] as is demonstrated by higher potassium losses in those who are higher transporters [18] Minerals Minerals more tightly bound to plasma proteins are typically not removed during dialysis and may accumulate in excess In contrast, minerals more weakly bound to proteins are removed more readily with low serum levels being more common [119] Elevated serum magnesium has been reported in patients receiving dialysis [56] Case reports indicate that very elevated magnesium levels that can contribute to symptoms are of concern, but mildly elevated magnesium lev- C L Nelms et al 474 els seem to have less clinical significance Elements such as chromium, manganese, lead, arsenic, aluminum, and vanadium are potentially toxic, especially with environmental or water contamination; therefore, supplementation is not advised [119, 120] Fluoride supplementation is also contraindicated in the pediatric dialysis patient Decreased frequency of standard dental fluoride treatments in children with CKD may be prudent as fluoride is poorly cleared with decreased kidney function [121] There is evidence that copper may have a role in the reduction of oxidative stress While there are reports of both elevated and depressed copper levels in pediatric dialysis patients, no clear recommendations for supplementation exist [113, 119, 120, 122] Low copper levels, which can be a manifestation of increased zinc exposure, can result in ESA-resistant anemia In turn, periodic evaluation of the zinc status [122] is suggested given zinc’s important role in many body functions including growth, immune function, and taste and smell Zinc is commonly reported to be below normal ranges in children receiving dialysis [56, 113, 119, 120, 122]; yet children on dialysis receiving standard supplementation were found to have varying serum levels [108] Selenium levels are commonly low in the pediatric dialysis patients [113, 119, 120, 122, 123] Accurate body selenium levels are more difficult to assess than zinc values [121] Variable levels for these minerals reported within the same study indicate the importance of individualization of micronutrient prescription Iron status is affected by decreasing kidney function, abnormal hepcidin level, and varying intake/tolerance of iron supplementation Iron status has a significant impact on anemia management, as discussed in Chap 32 Fluid Management Fluid control is pivotal in the management of children receiving dialysis to reduce complications such as hypertension and left ventricular hypertrophy that are associated with long-term cardiovascular risk Daily fluid requirements depend on the primary disease, corresponding urine output and the amount of fluid removed during dialysis [124] Patients with little or no urine output, or who achieve minimal fluid removal through dialysis, will require fluid restrictions Careful attention to sodium intake is essential as it greatly impacts thirst and fluid intake and ultimately the ability for patients to successfully manage daily fluid restrictions [125] Infants and children with polyuria require supplemental fluid intake over and above the usual intake goals, while restriction of fluid is indicated when patients become oliguric or anuric Both high and low fluid goals make meeting nutritional requirements more challenging [5] Patients with high fluid needs often forgo calories in favor of drinking large volumes of water in an attempt to normalize serum sodium levels Although rare in the setting of chronic dialysis, some patients who require additional fluid are unable to achieve daily fluid requirements Age-Based Considerations Infants and Young Children Children under the age of 5 years are most at risk for inadequate weight gain and growth and spontaneously consume less than their required energy needs [3, 126, 127] Anorexia and vomiting are common features of infants with CKD. Changes to taste perception can also occur early on in CKD and tend to worsen as renal function decreases Increased circulating cytokines that impact appetite and satiety result in reduced oral intake [128] The need for multiple and distasteful medications along with increased fluid requirements can cause oral aversions While young children have poor growth at the initiation of dialysis, they are most likely to have improved growth with adequate nutrition This may be due to the fact that the youngest children are the most likely to receive supplemental formula feedings, often via a tube, to achieve total intake [129] Children who graduate to an “all-oral” diet may consume foods that are high in calories, sugar, 26 Nutritional Assessment and Prescription for Children Receiving Maintenance Dialysis and fat CKiD data indicates that children who receive 500 or more calories from oral intake daily have calorie-dense diets which may include “empty calorie” items such as fast food, snacks foods and sugary foods, and beverages [16]; however, this may not be the case in regions of the world not consuming a “western” diet [130] Children with CKD also commonly suffer from severe reflux [131], delayed gastric emptying, uremia, and other issues that decrease appetite [126, 127], and this may have a more pronounced effect in the youngest children who, in the absence of foods with a high savory value, may consume inadequate nutrition nteral and Oral Formula or Breast Milk E Feeding There is currently no one commercially available formula that will “fit all” needs Enteral product selection and prescriptions should be tailored for positive long-term growth goals Feed prescriptions vary widely and change often, requiring dietitians to manipulate complex nutrient profiles Breast milk is the optimal choice for feeding most infants Human breast milk provides ideal nutrition, is associated with a low incidence of diarrhea, lowers infection rates, improves immunity, and has been felt to be a contributing factor to a lower risk of obesity in some populations [132] Breast milk’s bioavailability allows for ideal protein and nutrient intake, and its whey content is easily digestible making it a good choice for babies with kidney disease who are prone to delayed gastric emptying [133] Whenever expressed breast milk (EBM) is available, it should ideally be used as a component of the feed, and avoiding EBM waste should be prioritized [94] When breast milk is not available or no longer satisfies the nutrition needs of an infant with kidney disease, commercially available formula preparations should be considered, either as supplementation to breast milk or as the primary source of nutrition While feeding orally is ideal, the majority of infants receiving dialysis will need enteral feeding support [5] Tube feedings provide an average of 61% of total caloric needs in children with gastrostomies, suggesting the 475 need for nutrition support via supplemental feeding in this population [134] Furthermore, up to a third of feedings may be lost due to emesis, increasing the need for ongoing surveillance and diet adjustment [135] Once oral intake is evaluated for adequacy, enteral supplementation can be tailored to meet the total nutritional requirements Prescribing feeds to achieve biochemical stability is a priority as electrolyte derangements can have serious and sometimes deadly outcomes [5] Individualizing potassium content is required for children on dialysis who have inappropriate sodium and potassium ion exchange due to renal tubular disorders Phosphorus restrictions are not commonly needed for the infant or younger child, and most infant formulas are not high in phosphorus The use of a low-phosphorus product may actually necessitate supplementation In contrast, as oral intake increases, phosphorus restriction may be indicated Managing fluid volume is important in enteral feeding Abdominal fullness resulting from indwelling dialysate in the PD patient may make it challenging for the patient with polyuria to meet the increased fluid needs Increased intra- abdominal pressure with PD treatments can also lead to suboptimal formula/food intake For the patient whose fluids are restricted, feeds can be concentrated in a step-wise fashion with the goal of establishing feed tolerance and optimizing intake while minimizing the symptoms of poor gastric emptying, frequent emesis, and/or vomiting that may result from feeds with increased osmolarity Additional calories can be added via powdered low electrolyte and mineral modular products Protein modules can be titrated to individual protein needs While some renal-specific or nutrient-modified formulas are incomplete and therefore cannot be used as a sole source of nutrition, these formulas can be combined with other standard formulas to meet nutrient needs and to control potassium and phosphorus intakes Total osmolarity must be kept in mind in terms of renal solute load and tolerance Other approaches to control electrolyte and mineral intakes from commercial pediatric formula include pre-treatment of formula with C L Nelms et al 476 exchange resins and the use of adult renal formulations Adult renal formulations are energy dense (1.8 or 2.0 kcal/ml) and have reduced electrolyte and mineral contents [136] While both these approaches achieve reduction of potassium, the resulting mineral and electrolyte profiles are altered, requiring close monitoring of biochemical indices and vitamin and mineral intakes [94, 95, 136, 137] Additionally, adult renal preparations are casein-based formulas and may be less well tolerated than whey-based alternates As the number of formula components and preparation steps increases, so does the chance for errors in preparation [138] An increasing number of parents and caregivers are expressing a desire to feed their children with “more real food” and home- prepared blenderized tube feeds (BTF) BTF may be better tolerated than commercial formulas resulting in less reflux and constipation and an improved gut microbiome Successful use of BTF in medically complex children requires significant parental commitment and education regarding preparation techniques, food safety principles, and management of infection risk [139] The clinician must balance the most important priorities and specific needs in the formula choice [140] ransition to Oral Feeding T Children with CKD often experience delays in normal childhood development which may be evident in their progression with oral feeding Introduction of solids at age-appropriate times (e.g., 6 months for term infants) is recommended; however, the child with CKD may struggle with this goal [141, 142] Many young children with CKD cannot take any feeds orally Some may struggle with solids when coarser textures are introduced It is in turn common for toddlers who are well past year of age to need supplemental tube feeding When a child has consistently demonstrated failure with oral feeding or advancement of solids, it is appropriate to refer the child for therapy A behavioral psychologist trained in feeding therapy along with a speech language pathologist or an occupational therapist can provide strategies for improving feeding skills [141, 142] Caregivers may be easily discouraged by the challenges presented when feeding the child with CKD and may benefit from professional support Progression to age-appropriate feeding, especially post-transplant, is more rapid when the child has had exposure to normal feeding practices at developmentally appropriate times The use of gastrostomy tubes for feeding is associated with better oral outcomes compared to nasogastric feedings in which a feeding tube may irritate the throat or nose and create negative associations with things near or in the mouth [142–144] A team approach to managing gastroesophageal reflux, delayed gastric emptying, or other gastrointestinal comorbidities with medication and feeding adjustments helps remove barriers and improves the likelihood of oral feeding advancement It is important to determine which feeding plan may be most effective for the individual patient Nocturnal, continuous feeds allow hunger to develop during the day, while daytime bolus feeds emulate physiological feeding patterns In practice, a combination of daytime and nocturnal feeding may best meet the patient’s needs [5, 141, 142] Reducing stress around mealtimes and feeding in a relaxed environment may promote improved intake Allowing children to self-feed or dipping a pacifier in texture-appropriate foods may also help some children develop their feeding skills Promoting nonnutritive oral stimulation can provide a positive oral experience for the child with delayed oral intake If structural issues are suspected, immediate referral for evaluation prior to any further feeding therapy is recommended [141] Childhood Children of school age attend school to continue their social, emotional, and cognitive development Children with chronic illnesses may face challenges that negatively affect their school experience Those children with CKD are recorded to have some of the highest rates of absenteeism [145] Entering school coincides with a stage during which children are developing “eating compe- ... suggesting the 475 need for nutrition support via supplemental feeding in this population [134] Furthermore, up to a third of feedings may be lost due to emesis, increasing the need for ongoing... vitamin C balances [116] Daily supplementation with 250 mg of vitamin C showed improved intima media thickness and 473 cardiovascular status in a small study of children with CKD [117], and another... are more difficult to assess than zinc values [121] Variable levels for these minerals reported within the same study indicate the importance of individualization of micronutrient prescription Iron