Use of Renastep™ as an Oral Nutritional Supplement | Case Study
DESCRIPTION
A case study describing how the use of Renastep as an oral nutritional supplement allowed cessation of tube feeding in a child with Chronic Kidney disease.
Note:
Renastep is a Food for Special Medical Purposes.
This information is intended for use by Healthcare Professionals only.
Age: 4 years
Diagnosis: CKD stage 4 secondary to mitochondrial cytopathy
Relevant History:
Presented at 1 month of age with faltering growth, feeding difficulties, metabolic acidosis, raised serum creatinine and electrolyte abnormalities: hyperkalaemia, hyponatraemia (indicating a renal tubulopathy). Transferred from renal tubular clinic to multidisciplinary end stage nephrology clinic at 4 years of age for consideration of renal replacement therapies including live related renal transplant.
| Medication | Reason for Use |
| Sodium bicarbonate | To correct acidosis |
| Calcium resonium | An ion exchange resin that binds potassium |
| Sodium chloride | To correct hyponatramia |
| Sodium feredate | An iron supplement to prevent anaemia |
| Erythropoietin injection | A synthetic hormone which stimulates the bone marrow to produce red blood cells |
| Ubiquinone (Coenzyme Q) | To reduce symptoms related to mitochondrial disorder |
| Riboflavin | To improve mitochondrial function |
Anthropometry:
- Weight: 11.8 kg (<<0.4th centile) (-3 to -4SD)
- Length: 86.5 cm (<<0.4th centile) (-4 to -5SD)
- Height: age 2 years
- BMI: 50th centile
- Trends - slow growth and suspected low muscle mass (possibly related to underlying mitochondrial defect)
Feeding history:
Nasogastrically fed from 3 months of age. A percutaneous endoscopic gastrostomy (PEG) was inserted at 2 years of age (later changed to a button gastrostomy).
Intake
Low potassium powdered formula to ensure adequate nutrition.
The formula was given as a gravity bolus gastrostomy feed: 180 ml x 4 feeds per day at 9am, 1pm, 5pm and 9pm. Total volume = 720 ml.
Provides: 562 kcal, 8.4 g protein, 3.4 mmol potassium, 104 mg phosphate.
Will not drink the low potassium formula (except if used on breakfast cereal).
Theoretical requirements for height age (2 years)
Energy: 930 kcal (SACN 2011).
Protein: 14.5 g (UK DRV 1991).
Low potassium formula provided 60% energy and 58% protein requirements.
Oral appetite: variable/small
No fluid restriction.
Restricting intake of high protein and potassium foods.
High protein foods allowed at 1 meal per day only.
Breakfast:
Rice cereal 1-2 tablespoons
Low potassium milk formula
Lunch:
1 x 6 g protein portion (e.g. 2-3 chicken nuggets)
1 tablepoon of rice
2 teaspoons peas
Supper:
Pasta or noodles
Butter
Sweetcorn, carrots, broccoli, swede
Snacks:
Popcorn, small amount of ice cream
Drinks:
Blackcurrant squash
Sugary fizzy drinks
| Hospital reference range | Serum levels | |
| Sodium | 133 - 146 mmol/L | 140 |
| Potassium | 3.5 - 5.5 mmol/L | 4.9 |
| Total CO2 | 20 - 30 mmol/L | 24 |
| Urea | 2.5 - 6.0 mmol/L | 28.4 |
| Creatinine | 23 - 37 umol/L | 105 |
| Calcium | 2.22 - 2.51 mmol/L | 2.59 |
| PTH | 0.7-5.6 pmol/L | 2.4 |
| Phosphate | 1.20 - 1.80 mmol/L | 1.72 |
| Albumin | 35 - 52 g/L | 45 |
There was a need to find a low potassium nutritional supplement which could be taken orally and which would be simple to prepare and use.
Therefore it was agreed that Renastep would be trialled orally in place of the powdered low potassium gastrostomy feed. Aim for 2 x 125 ml bottles of Renastep per day (2 kcal/ml) providing 500 kcal, 10 g protein, 2.2 mmol potassium, 88 mg phosphate.
Patient enjoying Renastep; taking 2 x 125 ml bottles per day orally with no gastrointestinal symptoms reported. Stopped gastrostomy feeds. Cancelled the planned training for school to administer gastrostomy feeds. Improved appetite for foods as now on lower volumes of feeds.
Biochemistry:
| Hospital reference range | Serum levels | |
| Sodium | 133 - 146 mmol/L | 142 |
| Potassium | 3.5 - 5.5 mmol/L | 4.9 |
| Total CO2 | 20 - 30 mmol/L | 21 |
| Urea | 2.5 - 6.0 mmol/L | 35.1 |
| Creatinine | 23 - 37 umol/L | 123 |
| Calcium | 2.22 - 2.51 mmol/L | 2.50 |
| PTH | 0.7-5.6 pmol/L | 7.2 |
| Phosphate | 1.20 - 1.80 mmol/L | 1.86 |
| Albumin | 35 - 52 g/L | 46 |
- Introduce extra non-protein energy using a glucose polymer to help control serum urea level.
- Introduce a vitamin and mineral supplement as a gastrostomy bolus with water once per day to increase intake of some vitamins and micronutrients (which were lower in the smaller volume of Renastep).
- Review current food intake for organic and inorganic phosphate sources in view of increasing serum phosphate and PTH levels.
Renastep is a high energy, renal specific liquid feed that was successfully taken orally by a previously gastrostomy fed 4 year old child with Chronic Kidney Disease.
- Renastep has a mild vanilla flavour and was palatable as an oral supplement.
- The ready to feed liquid formulation was easier to use than their previous low potassium powdered product.
- Energy and protein requirements could be achieved in a smaller volume than the previous low potassium powdered feed.
- Serum potassium levels remained stable on changing to Renastep.
- Careful monitoring of vitamin and micronutrient intake may be necessary if changing to Renastep from an alternative low potassium formula. Some additional supplementation was necessary for our patient, as theoretical requirements for some vitamins and micronutrients were not met.
- The higher protein to energy ratio of Renastep (compared to other low potassium renal specific formulas), may lead to a need to use an additional energy source to prevent an increase in serum urea levels as in our case study.
Scientific Advisory Committee on Nutrition (SACN) Dietary Reference Values for Energy (2011). London: The stationary office. Dietary reference values for food energy and nutrients for the United Kingdom. Report no. 41 (1991) Report on Health and Social Subjects. London: HMSO.
