Nutrition and the Pediatric Patient with CKD

Cynthia J. Terrill

Caring for pediatric or adolescent patients with chronic kidney disease (CKD), including those with chronic renal insufficiency and those on dialysis,  presents unique and varied challenges for the entire healthcare team. One major challenge is balancing the nutritional requirements of these patients in order to promote appropriate growth and development with the need to control the biochemical and metabolic consequences associated with the disease state.

Barriers to Achieving Nutritional Goals

There are several barriers to achieving the nutritional goals in the pediatric renal population. These include the anorexia and associated poor calorie and protein intake frequently seen in patients with CKD, metabolic acidosis and hormonal abnormalities, the use of corticosteroids in the treatment of certain kidney disorders and as immunosuppressive therapy, and psychosocial and developmental issues.   Each of these areas needs to be addressed and the appropriate intervention implemented.  

Changes in taste due to renal failure, metabolic abnormalities and dietary restrictions frequently make it difficult for children with CKD to meet their nutritional needs. The anorexia and associated poor calorie and protein intake frequently seen in children with CKD can negatively impact linear growth and weight gain (Norman, Macdonald, & Watson, 2004). Correction of the metabolic acidosis with base supplements such as sodium bicarbonate or sodium citrate and dialysis therapy can help to promote increased intake and optimize linear growth and weight gain. Additionally, treatment of the anemia associated with CKD using erythropoietin and iron supplementation may help to promote improved oral intake. Finally, a more liberal diet may help the patient more successfully meet nutritional needs. However, it is important to monitor laboratory values closely and adjust the diet as appropriate to maintain optimal biochemical control.  

Linear growth is also impacted by calcium and phosphorus balance. It is, therefore, important to pay careful attention to serum calcium, phosphorus, and parathyroid hormone (PTH) levels in order to maximize growth.  Dietary phosphorus restriction and use of phosphate binders are essential in controlling serum phosphorus levels. Vitamin D metabolites such as calcitriol (1,25 dihydroxycholecalciferol) are used to prevent and treat hyperparathyroidism and CKD mineral and bone disorders. If linear growth does not improve after ensuring adequate calorie and protein intake and appropriate treatment of metabolic acidosis and renal osteodystrophy, the use of recombinant growth hormone therapy should be considered. Although pediatric patients with CKD often have normal growth hormone levels in their bodies, there may be increased amounts of binding proteins and, therefore, less active growth hormone. Giving recombinant growth hormone as a subcutaneous, daily injection can improve linear growth in children with renal failure who still have growth potential (open growth plates) (Mahan, Warady, Consensus Committee, 2006).

Corticosteroids, such as prednisone, are often used to treat certain types of kidney disease, including glomerulosclerosis and IgA nephropathy. They may also be used as part of the immunosuppressive therapy following renal transplantation. While they can effectively treat these medical conditions, they have been negatively associated with linear growth in children. Additionally, high dose steroids can contribute to excessive weight gain due to reported stimulation in appetite (Rock & Secker, 2004). It is important to monitor linear growth and weight gain closely in children who are on corticosteroids. Ideally, the lowest possible dose of steroids should be used in order to minimize the impact on linear growth and potential for excess weight gain.

Children with CKD may experience feelings such as depression, anger, fear, and denial related to their medical condition. Additionally, CKD can contribute to lethargy and increased fatigue, mental status changes, confusion, and poor memory. There also may be delays in psycho-motor development and oral aversion, particularly in children born with CKD. Families may experience financial difficulties associated with their child’s chronic disease due to missed work or loss of employment, high medical bills, lack of medical insurance, and specialized dietary needs such as a high protein diet. All of these issues can make it more difficult to meet the nutritional needs of the child with CKD and should be appropriately addressed by the health care team (Nevins, 2005).

Nutritional Assessment

AThe nutritional assessment of the pediatric patient with CKD involves the use of multiple parameters (Foster & Leonard, 2004) and is best performed by an experienced pediatric renal dietitian. However, the renal nursing staff can be instrumental in helping to obtain accurate anthropometric measures and alerting the dietitian to abnormalities in laboratory values and changes in the patient’s medical condition. Interval measurements of growth and nutrition parameters should be obtained on a regular basis (NKF, 2000). These include height or length (in children less than 2 years of age or for those who are unable to stand without assistance), weight, and head circumference (in children less than 3 years of age). Mid-arm circumference (MAC) and triceps skinfold (TSF) thickness are also helpful in assessing the patient’s nutritional status. Additionally, weight for length and Body Mass Index (BMI) should be evaluated. Infants and small children may require more frequent assessment to help monitor adequacy of intake, tolerance to feedings and growth. All measurements should be plotted on standardized growth charts developed by the Centers for Disease Control and Prevention (CDC, 2000) and assessed for trends on a regular basis.

Length measurements should be done on a measuring board by two people in order to get an accurate measurement. One person holds the crown of the head against the headboard and the other person moves the footboard up to the heels of the infant’s feet as legs are straightened. When obtaining height measurements, the child should remove his or her shoes and stand on the floor, looking straight ahead. Both length and height measurements should be recorded to the nearest 0.1 cm.

To obtain an accurate weight, an infant should be undressed completely and the weight obtained on an infant scale. Older children may be weighed standing up in light clothing without footwear. The weight should be recorded to the nearest 0.1 kg. It is important to consider the fluid status of the patient when evaluating for weight gain since fluid weight gain may be misinterpreted as actual weight gain and increase in lean body weight. Pediatric patients on dialysis should be weighed both before and after a dialysis treatment. Blood pressure measurements, heart rate, and clinical appearance may be helpful in assessing whether a patient is at his or her “dry weight” following a dialysis treatment. The maximum head circumference should be measured in children up to age 36 months and recorded to the nearest 0.1 cm.  Head circumference measurements help in assessing the adequacy of nutrient intake and are typically reflective of brain growth and development. A sudden acceleration in head growth may signal a change in medical condition such as hydrocephalus.  Mid-arm circumference and triceps skinfold thickness should be obtained by the same person on a regular basis when the patient is at dry weight. Serial monitoring of these parameters can detect changes in somatic protein stores and fat stores, and may be helpful in determining the etiology of changes in weight. 

In addition to accurate anthropometric measurements, laboratory data are essential in assessing the patient’s nutritional status and needs. Albumin is a measure of visceral protein stores and is the most frequently used marker of nutritional status (NKF, 2000). Albumin levels may be decreased when the patient is not adequately meeting calorie and protein needs. It may also be decreased in patients with urinary protein losses or nephrotic syndrome, following surgical procedures, or in patients with liver disease or peritonitis. Patients on peritoneal dialysis will also experience increased protein losses in their dialysate solution, which may result in hypoalbuminemia (Rock & Secker, 2004). They, therefore, require a higher protein intake than patients on hemodialysis. Measurement of blood urea nitrogen (BUN) can be helpful in assessing the protein intake of the pediatric patient with CKD. A low BUN in relation to serum creatinine frequently reflects poor protein intake while an excessively high BUN may suggest dehydration, excess protein intake,or catabolism. Other laboratory data that need to be evaluated include serum sodium, potassium, calcium, phosphorus, intact or bio-intact PTH, hematocrit, iron studies (iron, percent saturation, ferritin), and CO2 levels.  

Dietary modifications may be made frequently, but dietary restrictions should only be initiated when indicated necessary by laboratory values, medical condition and medical therapy. It is particularly important to individualize the diet plan for the pediatric patient. Modifications in calories, protein, sodium, potassium, phosphorus, and fluid intake may be necessary depending on the patient’s medical condition and therapy, dialysis modality, medications, blood pressure, fluid balance, laboratory values, nutritional status, growth and weight gain, and age.

Gastrointestinal disturbances such as nausea, vomiting, diarrhea, constipation, delayed gastric emptying, and early satiety are frequently seen in children with CKD and need to be considered when evaluating the nutritional status and dietary needs of pediatric patients with CKD. These can all negatively impact the patient’s ability to meet nutritional needs and may necessitate dietary modifications and adjustments in medications and medical therapy. The nephrology nurse can be particularly helpful in alerting the rest of the healthcare team of these conditions so that they can be addressed and treated appropriately.  Proton-pump inhibitors, H-2 antagonists, motility agents, anti-diarrheal agents, antimicrobial agents and probiotic therapy may be helpful in treating these problems, although dosages need to be adjusted appropriately for renal failure (Smith & Garney, 2004).

Nutrition For Infants With Pediatric Renal Disease

nMeeting the nutritional needs of infants with CKD can be especially challenging since inadequate nutrient intake is common in this population. Decreased appetite and oral aversion are frequently observed with the infant refusing all oral liquids and solids. Enteral feedings (nasogastric, nasojejunal, gastrostomy or gastro-jejunostomy tube) may be necessary to meet 100% of nutritional needs (Ledermann, Spitz, Moloney, Rees, & Trompeter, 2002) and can be a source of frustration for parents due to frequent tube dislodgement, clogging of the tube, malfunction of the feeding pump, vomiting, and diarrhea. Additionally, parents and caregivers are frequently extremely anxious about feeding their young children with kidney disease and may require increased emotional support from the healthcare team.
Specialized infant formulas designed for children with CKD may be necessary to meet nutritional needs and maintain optimal biochemical control. Similac PM 60/40  and Good Start  are two formulas that are lower in sodium, potassium, and phosphorus with a lower renal solute load than other infant and pediatric formulas.  They typically should not be concentrated due to increased electrolyte and mineral content. Modular components of protein (i.e., ProCel, RESOURCE Beneprotein powder), carbohydrate (Polycose powder, RESOURCE Benecalorie, Caloreen) and fat (vegetable oils, Microlipid) can be added to increase the caloric density and protein content of the formula without increasing mineral and electrolyte content. Renal formulas, (Nepro CHO Steady and Suplena CHO Steady, Renalcal, NovaSource Renal) which are calorically dense, high or low in protein, low in electrolytes and phosphorus, and designed for adults with CKD, are not usually recommended for children less than 2 years of age due to the increased osmolality and inappropriate vitamin and mineral content of these formulas.  When used, it may be necessary to dilute these formulas to one- quarter to one-half strength to achieve tolerance.  Serum magnesium levels should be monitored closely since the magnesium content is significantly higher in these adult renal formulas than in infant formulas (Rock & Secker, 2004).  
Fluid needs in infants with non-oliguric CKD (usually due to congenital renal dysplasia), may be significantly increased, due to the infant’s inability to concentrate urine There also may be increased urinary sodium losses, necessitating sodium supplementation to achieve optimal growth and weight gain (Parekh et al., 2001).  Fluid restriction for infants and toddlers with CKD on dialysis may make it more difficult to meet nutritional needs for growth and weight gain. Calorie and protein dense formulas, using modular components, are frequently necessary to meet calorie and protein needs without compromising good biochemical control. However, these formulas may exacerbate gastrointestinal disturbances such as vomiting and diarrhea. Frequent adjustments in the formula, feeding modality, and nutritional plan by the pediatric renal dietitian, in conjunction with the pediatric renal team, is often necessary to achieve optimal nutrient intake and promote appropriate growth and weight gain.

References
Centers for Disease Control and Prevention. (2000).  2000 CDC Growth Charts:  United States. Retrieved December 28, 2006 from http://www.cdc.gov/growthcharts.
 
Foster, B.J., & Leonard, M.B. (2004). Measuring nutritional status in children with CKD. The American Journal of Clinical Nutrition, 80, 801-814.
 
Furth, S.L. (2005). Growth and nutrition in children with CKD. Advances in CKD, 12, 366-371.

Ledermann, S.E., Spitz, L., Moloney, J., Rees, L., & Trompeter, R.S. (2002). Gastrostomy feedings in infants and children on peritoneal dialysis. Pediatric Nephrology, 17(4), 246-250.
 
Mahan, J.D., Warady, B.A., & Consensus Committee (2006).  Assessment and treatment of short stature in pediatric patients with CKD:  a consensus statement. Pediatric Nephrology, 21(7), 917-930.
 
National Kidney Foundation (NKF) (2000). Clinical practice guidelines for nutrition in chronic renal failure. American Journal of Kidney Disease, 35(6 Suppl 2),S1-140.

Nevins, T.E. (2005). “Why do they do that?” The compliance conundrum. Pediatric Nephrology, 20(7),845-848.   
Norman, L.J., Macdonald, I.A., & Watson, A.R. (2004).  Optimising nutrition in chronic renal insufficiency – growth.  Pediatric Nephrology,19(11),1245-1252.
  
Parekh, R.S., Flynn, J.T., Smoyer, W.E., Milne, J.L., Kershaw, D.B., Bunchman, T.E., et al (2001). Improved growth in young children with severe chronic renal insufficiency who use specified nutritional therapy. Journal of the American Society of Nephrology, 12, 2418-2426.
 
Rock, J., & Secker, D. (2004). Nutrition management of CKD in the pediatric patient. In L. Byham-Gray, K Wiesen (Eds.), A Clinical Guide to Nutrition Care in Kidney Disease (pp. 127-149). Chicago:  American Dietetic Association.

Smith, B., & Garney, P. (2004). Medications commonly prescribed in CKD. In L. Byham-Gray, K Wiesen (Eds.), A Clinical Guide to Nutrition Care in Kidney Disease (pp. 175-194). Chicago:  American Dietetic Association.