3.1 Breastfeeding is the preferred method for feeding an infant with CKD. (Level X; strong recommendation).
3.2 When breastfeeding is not possible or expressed breastmilk is not available in adequate amounts for the infant with CKD, we suggest that whey-dominant infant formulas be used. (Level A; strong recommendation).
3.3 We suggest that breastmilk and infant formulas should be fortified when there is a prescribed fluid restriction or when a more energy or nutrient dense feed is required to meet nutritional requirements. (Level A ; strong recommendation).
3.4 We suggest that the concentration of feeds and addition of dietary supplements are prescribed in a gradual manner in order to maximize acceptance and tolerance. (Level D; weak recommendation).
Evidence and rationale
Breastmilk is the best source of nutrition for infants (
65), including those with CKD2–5D who may benefit from its low renal solute load. Standard whey-dominant infant formulas have a protein and electrolyte content closer to that of breastmilk than casein-dominant formulas, so are the preferred alternative and may be beneficial beyond the first year of life. Do not use soya infant formulas under 12 months of age due to their high phytoestrogen content, unless there is a specific medical indication.
The nutritional content of infant formulas may be concentrated in a smaller volume when there is a need for fluid restriction, or when normal feed volumes exacerbate vomiting and gastro-esophageal reflux. Most standard infant formulas are reconstituted to an approximate 13% concentration (i.e., 13 g powder to 100 ml water, providing 67 kcal and 1.3 g protein per 100 ml). It is suggested that this concentration may be increased daily by 1–3%, up to 20% (i.e., 20 g powder to 100 ml water), depending on local practices and the infant’s tolerance of feed changes. Infant formula powder may also be added to expressed breastmilk (EBM) at a concentration of 3–6% (i.e., 3–6 g infant formula powder to 100 ml EBM), increasing the total energy density up to 1 kcal/ml. Breastmilk fortifier may also be used for preterm infants.
Concentrating the formula should be done gradually to ensure tolerance since the increase in osmolality (
66) may cause diarrhea, vomiting, and gastro-esophageal reflux. It also increases the renal solute load and may lead to excessive intakes of phosphate, potassium, and other minerals and vitamins. Toxic levels of vitamin A are of particular concern (
67). In contrast, the majority of water-soluble vitamins are below the dietary reference intake (DRI) (
68,
69). In patients on dialysis, certain vitamins (water-soluble vitamins B1, B5, B6, folic acid, vitamin C) and zinc are lost excessively in the dialysate; these may need to be supplemented over and above the levels provided by the formula to meet recommended intakes. Recommendations regarding the vitamin intake for children with CKD are included in the KDOQI guidelines (
3).
An alternative is to use an infant formula at a normal concentration (or EBM if available) and to add protein powder and/or energy modules (glucose polymers, fat emulsions, or combined carbohydrate and fat preparations) to design a patient-specific profile for energy and protein, with attention to vitamin and mineral supplementation as necessary (
24,
70,
71). This method of fortification is particularly used if concentrating the infant formula provides an intake of vitamin A, potassium, or phosphate beyond desirable levels. A simple recipe and caregiver education are required to reduce errors in formula preparation (
72). Energy and nutrient dense liquid infant formulas are available commercially and may be useful. The addition of glucose polymers, fat emulsions, and protein powders to standard infant formula and EBM can be used for oral feeding or tube feeding. If a mother wishes to continue breastfeeding, this should be prioritized and incorporated into the feeding plan as long as the infant’s overall nutritional intake is not compromised.
To achieve optimal growth in the healthy infant with appropriate deposition of lean and fat tissue, the PE ratio of the infant formula should ideally be within the range 7–12%; a high PE ratio is required for accelerated weight gain or catch-up growth (Supplementary Table
5) (
46). In CKD, the challenge is to preserve the PE ratio while adding non-protein energy sources (carbohydrate and fat) to formula in order to control abnormal blood biochemistry, such as elevated urea, phosphate, or potassium levels. In these situations, it is important to ensure that at least the SDI for protein is provided. A PE ratio of 5.3–6.4% supported weight gain and linear growth in children aged 0–2 years, provided at least 100% of protein requirements were given (
21), the lower PE ratio reflecting an increase in energy provision rather than a low protein intake.
Glucose polymers may be added in increments, e.g., 1% daily (1 g extra added to 100 ml formula or EBM per day, yielding an additional 4 kcal/100 ml). Gradual increases will allow for identification of the concentration at which the infant becomes intolerant (developing loose stools, increased vomiting). Tolerance to increased carbohydrate concentration depends on the age of the infant, and the maturity and absorptive capacity of the gut, with some infants more tolerant to a more rapid addition of a glucose polymer.
Fat emulsions may be used and should also be added incrementally, e.g., 1% daily (1 ml added to 100 ml formula or EBM per day) to provide an increase of 0.5 g fat per 100 ml (an additional 5 kcal/100 ml). The increased fat content may delay gastric emptying and cause nausea and vomiting. See Table
2 for suggested percentage concentrations of carbohydrate and fat that may be tolerated.
Table 2
Suggested addition of energy modules to formulas
Glucose polymer | < 6 months | 3–5 g (+ 7 g CHO from infant formulaa) | 10–12 |
| 6 months–1 year | 5–8 g (+ 7 g CHO from infant formulaa) | 12–15 |
| > 1 year | 8–18 g (+ 12 g CHO from pediatric formulaa) | 20–30 |
Fat emulsion (50% fat content) | < 1 year | 3–5 ml (+ 3.5 g fat from infant formulaa) | 5–6 |
| > 1 year | 9 ml (+ 4.5 g fat from pediatric formulaa) | 9 |
Hyperkalemia occurs as CKD progresses and is more pronounced in patients with metabolic acidosis. Usually reduced potassium intake is indicated (
3), but hyperkalemia can result from cell catabolism when there is deficient energy intake. This can be resolved by the addition of energy modules to the infant’s usual formula or EBM.
Protein powders are added to formulas or EBM to provide a specific amount of protein per kilogram of body weight. Additional protein is particularly important for the child on PD to compensate for protein losses in dialysate (
60). Protein intake should be increased by at least 0.15–0.3 g/kg/day for children on PD, 0.1 g/kg/day for HD (
3). Supplements should be added in small increments, 0.1 g protein/kg/day, and urea levels measured to detect excessive intake (i.e., urea levels above expected for degree of CKD). On occasion, measurement of dialysis protein losses may help guide a plan for protein supplementation.
3.5 Solid foods should be introduced as recommended for healthy infants, with progression to varied textures and content according to the infant’s cues and oral motor skills. We suggest that all children eat a healthy, balanced diet with a wide variety of food choices, as for the general population, taking into account possible dietary limitations. (Level D; weak recommendation).
3.6 Oral feeding is the preferred route whenever possible. Oral stimulation is desirable, even if oral intake is limited, to prevent the development of food aversion. (Level C; weak recommendation).
Evidence and rationale
Whilst exclusive breastfeeding for the first 6 months of life is recommended by the WHO and supported by a systematic review (
65), the age when solid foods are introduced for infants with CKD should be managed individually. Delayed exposure to pureed and more textured foods may cause feeding problems (
73). The nutritional content of solid food must be balanced against that provided by the formula in order to achieve optimum intake of energy, protein, and other nutrients. Dietary limitations in potassium and phosphate may be necessary according to the stage of CKD and abnormal blood biochemistry. A low potassium or phosphate formula may be given so that dietary restrictions can be liberalized to allow a greater variety of foods to be offered. A more liberal oral intake may encourage more normal development and behaviors around food.
From 1 year of age, commercially available fortified milk drinks (with a suitably low phosphate and potassium content) may be useful as they contain iron, vitamin D, and n-3 polyunsaturated fatty acids, which may enhance the diet of the toddler with CKD. Also known as “Young Child Formulas,” they are not routinely recommended for healthy children (
74).
Infants and young children with CKD2–5D may be reluctant to take an oral diet. At the same time, tube feeding is associated with long-lasting feeding difficulties, such as chewing and swallowing problems, food refusal, panic attacks (
75), and poor development of oral motor skills (
73). An important aspect of nutritional treatment is therefore to enable as normal development of feeding and eating as possible. When there are significant feeding difficulties, speech and language therapy may help caregivers with the provision of oral feeding and with non-nutritive oral stimulation; input from a psychologist, including family therapy, may be considered (
73).
Whilst encouraging an oral diet, there is a need to educate families about healthier food choices at the time of introduction of solids in order to influence later dietary habits. Besides undernutrition, obesity is common in the CKD population and the frequency is similar to that of the normal population. A food frequency questionnaire (FFQ) in 658 children aged 2–18 years with mild to moderate CKD in North America has highlighted some undesirable eating habits (
44). Fast foods were a major contributor of sodium, phosphorus, energy, and fat intake, with cow’s milk and milk products contributing 7.7% of energy, 13.8% of protein, 4.6% of sodium, 20.3% of phosphate, and 15.9% of potassium intakes. Dietary and lifestyle changes to achieve weight control are discussed by KDOQI (
3).
3.7 We suggest prompt intervention once deterioration in weight centile is noted. Oral nutritional supplementation should be started in children with inadequate dietary intake, after consideration of medical management of correctable causes of reduced intake. (Level B, moderate recommendation).
Evidence and rationale
Growth is most rapid in the first year of life, and failure to gain weight is the signal for intervention. If weight is static for just 2 weeks in the first 3 months of life, there is a loss of 1 centile; if static for 4 weeks, 2 centiles are lost; at 6 months of age, there is a loss of 1 centile after a 3 week period of no weight gain; and at 9 months, 1 centile is lost after 4 weeks of static weight. Weight and/or head circumference measurements are more sensitive markers of poor growth in infants with CKD when length/height measurements are often inaccurate.
The first step in response to poor weight gain is to address any correctable causes of reduced dietary intake, such as gastro-esophageal reflux/vomiting (by means of feed thickeners, alginates, antacids, histamine H2 receptor antagonists, proton pump inhibitors, sucralfate, prokinetics), acidosis, volume overload, or inadequate dialysis. Children with CKD may also not achieve adequate oral intake due to reduced appetite, altered smell and taste, and abnormal hormone regulation (
76‐
88) (Supplementary Table
6). When inadequate energy and protein intake persists, nutritional supplementation should be instituted. Many studies in children with CKD suggest that growth deteriorates without supplemental feeding and that with dietary intervention by the oral route or with enteral tube feeding, this deterioration can be diminished (
18,
21,
22,
29,
36,
38,
40,
43,
89‐
95). In children with salt-wasting forms of CKD, salt supplementation is also necessary for optimal growth (
3).
Energy and protein modules can be added to EBM, standard infant formulas, and infant renal specific formulas. Alternatively, standard pediatric enteral formulas can be fortified if the child will drink them. Standard adult enteral and renal specific formulas can be modified, if necessary, to meet the nutritional requirements of infants and children, but with particular attention to their vitamin and mineral content, which may be excessive.
For those children who are eating, these modules can also be added to normal foods and beverages to meet energy and protein requirements. Where vitamin and mineral intake is also lacking, the first line of treatment is to give nutritionally complete oral liquids (also known as oral nutritional supplements or sip feeds) suitable for toddlers, older children, and adolescents. If there are concerns with elevated electrolyte levels, a palatable high energy pediatric renal specific oral nutritional supplement can be used, when available.
Glucose polymers can be added to beverages, starting with 5% (5 g added to 100 ml) and increasing to 20–30% as needed, and also to “liquid” foods such as porridge/hot breakfast cereals and custards/soft desserts. Sugar and glucose may also be used, but the quantity may be limited due to their sweet taste and osmotic effect on the gut. Extra fat in the form of vegetable margarines or oils (preferably those with a high content of omega-3 fats, such as olive, walnut, or rapeseed oil), and jams, honey, or syrups can be added to foods. Other options include alternative “milks” derived from plants, such as soy, oat, almond, or coconut, without calcium phosphate fortification. It is not advisable to give rice milk to infants and young children due to its high arsenic content. Fruit juices, or alternatively concentrated fruit flavorings (cordials) if there is hyperkalemia, can be provided; protein-free milk replacement drinks, which have low phosphate contents, can serve as a supplement. Glucose absorbed from PD fluid (
41,
42) contributes to total energy intake.
It is rarely necessary to add protein modules to foods for children with CKD2–5, but they may be useful for those on dialysis, choosing low phosphate preparations. Most liquid oral renal specific supplements designed for adults are low volume and can be provided between meals in small portions without compromising appetite.
No recommendation can be made for using dietary supplements of essential amino acids and ketoacids in children with CKD. In a trial with 20 children and adolescents, a low protein diet (0.6 g/kg/day) with ketoacid supplements led to a statistically significant (
p < 0.001) increase in height SD (from − 1.93 ± 1.76 to − 1.37 ± 1.58) when compared to a diet providing the RDA for protein (
96). A study of 20 infants with an eGFR < 30–75 ml/min/1.73 m
2 (not tube fed), and a diet containing 1.8–2.2 g protein/kg/day with supplemental essential amino acids accounting for 20% of the protein intake showed a decrease in weight and height SD from birth to 12 months: − 0.26 to − 1.53 and − 0.56 to −1.63, respectively (
97).
3.8 We suggest that supplemental or exclusive enteral tube feeding should be commenced in children who are unable to meet their nutritional requirements orally, in order to improve nutritional status. (Level B, moderate recommendation).
Evidence and rationale
Several retrospective studies in children with CKD have shown improvement in weight/BMI SD with tube feeding (
18,
21,
22,
91‐
95). All but two of these studies (
91,
95) also showed an improvement in height SD. Although most of the available evidence is for children under the age of 2 years, one study reported an increase in weight and height SD specifically for children aged 2–5 years with tube feeding (
21). In these studies, tube feeds provided as much as 100% of requirements, while others were supplemental to oral intake.
Three studies have not shown an association between tube feeding and growth. In a questionnaire-based nested case-control study on 137 dialysis patients, where 70% of the children received tube feeds, there were no significant differences in weight or height SDS up to 1 year after dialysis initiation in patients receiving supplemental feedings compared to those not receiving supplemental feedings (
38). Two smaller prospective studies also failed to detect an association between energy intake and growth (
29,
97).
Commercial formulas and expressed breastmilk are preferred for tube feeding and can be supplemented, if necessary, as described above. Parents wishing to prepare their child’s tube feeds by blending foods should be counseled by a qualified dietitian about safety issues with this practice, including nutritional quality, microbial contamination, and appropriate equipment and administration (
98).
When oral or tube feeding is not sufficient or possible, usually as a result of intestinal failure, parenteral nutrition may be needed and the prescription must be tailored for the child with CKD. Intradialytic parenteral nutrition (IDPN) in children is rarely indicated and does not confer a benefit over enteral feeding (
99). Studies are scarce (
100‐
102) and no recommendations for its use can be given.
Ongoing oral stimulation is important in tube fed children to help in the transition to normal feeding once they have had a successful transplant (
103,
104).