Using Renastart™ in the management of congenital nephrotic syndrome | Case Study
Description
A case study on the use of Renastart in the management of an infant with congenital nephrotic syndrome.
The patient is a 4 week old female who was diagnosed with congenital nephrotic syndrome.
Weight (Kg): 3.7
Percentile on the growth chart: 50th
The child presented with acute renal failure, oliguria and nephrotic range proteinuria at the age of 4 weeks.
Biochemistry at diagnosis
| Potassium (mmol/l) | ⬆ 7.5 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | ⬆ 10.7 Ref Range* (3.1-7.4) |
| Urea (mg/dl) | ⬆ 99 Ref Range* (6-45) |
| Creatinine (mg/dl) | ⬆ 1.32 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 17 |
Medical management
The child was commenced on peritoneal dialysis (PD) and intubated (due to metabolic acidosis). Total Parenteral Nutrition (TPN) was initiated as per hospital protocol.
After stabilisation, the child was started on expressed breast milk via nasogastric tube. Blood potassium, phosphate and urea levels returned to be within reference range. Urine production was normal and TPN stopped.
Biochemistry after initial management and stabilisation
| Potassium (mmol/l) | 3.8 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | 4.9 Ref Range* (3.1-7.4) |
| Urea (mg/dl) | 12 Ref Range* (6-45) |
| Creatinine (mg/dl) | ⬆ 0.72 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 34 |
* Hospital reference ranges.
Weight (Kg): 4.1
Percentile on the growth chart: 3rd
At 9 weeks of age, the child’s kidney function started to decline (chronic kidney disease). Dietetic intervention was necessary as blood potassium level started to increase.
Biochemistry
| Potassium (mmol/l) | ⬆ 5.0 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | ⬇ 3.0 Ref Range* (3.1-7.4) |
| Urea (mg/dl) | 26 Ref Range* (6-45) |
| Creatinine (mg/dl) | ⬆ 0.82 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 29 |
Calculation of nutritional requirements
96-100 kcal/kg/day1 . 2.4 g protein/kg1 . Potassium restriction required due to raised blood potassium. No fluid restriction was in place.
Dietary intake
552 ml expressed breast milk at 23 ml/hr. Started at 5 ml/hr and gradually increased to 23 ml/hr with the aim to further increase the rate until energy requirements were met.
Feed provides
| Energy | 382 kcal (93 kcal/kg) |
| Protein | 6.24 g (1.5 g/kg) |
| Potassium | 260 mg (1.6 mmol/kg) |
| Phosphorus | 83 mg |
| Sodium | 72 mg (0.8 mmol/kg) |
Aim
Provide an enteral feed which is lower in potassium but still provides enough protein and phosphate.
Feeding plan
Tube feeding – continuous 23 ml/hr – Use Renastart exclusively for a limited period of time to reduce potassium intake and thus blood potassium levels.
23 ml/hr of 20% Renastart for 24 hours = 552 ml
Feed provides
| Energy | 522 kcal (135 kcal/kg) |
| Protein | 8.28 g (2.0 g/kg) |
| Potassium | 121 mg (0.8 mmol/kg) |
| Phosphorus | 105 mg |
| Sodium | 265 mg (2.8 mmol/kg) |
The child’s electrolytes were monitored regularly.
Biochemistry after first dietetic intervention
| Potassium (mmol/l) | ⬇ 3.0 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | 4.4 Ref Range* (3.1-7.4) |
| Urea (mg/dl) | 45 Ref Range* (6-45) |
| Creatinine (mg/dl) | ⬆ 1.39 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 17 |
After 24 hours, the child’s blood potassium level had reduced to below the reference range. Therefore, the feeding regime was adjusted to increase the potassium intake.
Adjusted feeding regimen
Feeding plan:
Tube feeding - continuous 23 ml/hr - 276 ml Renastart and 276 ml breast milk
over 24hrs = 552 ml
55 g Renastart (20% dilution) + 276 ml breast milk
New feeding regimen provides
| Energy | 465 kcal (113 kcal/kg) |
| Protein | 7.58 g (1.85 g/kg) |
| Potassium | 191 mg (1.2 mmol/kg) |
| Phosphorus | 94 mg |
| Sodium | 168 mg (1.8 mmol/kg) |
Biochemistry after second dietetic intervention
| Potassium (mmol/l) | 3.8 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | 4.4 Ref Range* (3.1-7.4) |
| Urea (mg/dl) | ⬇ 1 Ref Range* (6-45) |
| Creatinine (mg/dl) | ⬆ 1.73 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 16 |
The child’s potassium level increased to be within the normal range. The child’s electrolyte levels continued to be monitored regularly and feed was adjusted as needed following regular dietetic reviews.
| Weight (Kg) | 8.3 |
| Height (cm) | 75.5 |
| Percentile on the growth chart | Weight: < 3rd Height: < 3rd |
At 2 years of age, haemodialysis rather than PD was commenced and the child had a total nephrectomy. A fluid restriction was in place and the blood results showed an increasing phosphate and potassium level.
Biochemistry
| Potassium (mmol/l) | ⬆ 5.5 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | ⬆ 2.22 Ref Range* (1-1.9) |
| Urea (mg/dl) | ⬆ 117 Ref Range* (12-48) |
| Creatinine (mg/dl) | ⬆ 3.55 Ref Range* (0.24-0.41) |
| GFR (ml/min) | 12 |
Calculation of nutritional requirements
78-82 kcal/kg/day1 . 1.2 g protein/kg1 . Potassium and phosphate restriction required due to raised blood potassium / phosphate. Fluid restriction max 500 mL/day. Phosphate: < 400 mg/day.
Medications
| Medication | Reason for use |
| Alphaleo | Active vitamin D supplement |
| Omeprazole | Gastroesophageal reflux |
| Soluvit | Water soluble vitamins |
| Calcium Carbonate | Phosphate binder |
| Kayexalate | Potassium binder |
| Erythropoeitin | Promote red blood cell production |
| Venofer | Iron deficiency anaemia |
| Genotonorm | Human growth hormone |
| Forlax | Laxative |
| Amlodipine | High blood pressure |
Feeding regimen
95 g standard infant formula, 5 g protein supplement, 25 g maltodextrin (5% dilution) made up to 500 ml with water.
Feed provides
| Energy | 606 kcal (60 kcal/kg) |
| Protein | 14.27 g (1.43 g/kg) |
| Potassium | 554 mg (1.42 mmol/kg) |
| Phosphorus | 393 mg |
| Sodium | 190 mg (0.83 mmol/kg) |
The child required more energy and protein but less phosphate.
Therefore, feeding regimen was adapted:
35 g Renastart, 78 g standard infant formula, 10 ml fat emulsion, 5 g protein supplement, 25 g maltodextrin (5% dilution) made up to 500 ml with water.
Feed provides
| Energy | 735 kcal (86 kcal/kg) |
| Protein | 15.10 g (1.82 g/kg) |
| Potassium | 494 mg (1.53 mmol/kg) |
| Phosphorus | 361 mg |
| Sodium | 240 mg (2.55 mmol/kg) |
Biochemistry after starting the new adapted feeding regimen:
| Potassium (mmol/l) | 4.3 Ref Range* (3.6-4.8) |
| Phosphate (mg/dl) | 1.65 Ref Range* (1-1.9) |
| Urea (mg/dl) | ⬆ 137 Ref Range* (12-48) |
| Creatinine (mg/dl) | ⬆ 1.73 Ref Range* (0.17-0.42) |
| GFR (ml/min) | 16 |
The child had regular dietetic reviews with the feed being adjusted as needed according to the biochemistry and nutritional requirements. The child had a transplant at age 4.
* Hospital reference ranges
Renastart is specifically designed for the dietary management of paediatric kidney disease. It can be used when a lower intake of potassium and phosphate is needed, whilst still providing other essential nutrients such as energy, protein, vitamins and minerals, as demonstrated in this case study.
1. Royle, J. Chapter 12: Kidney Disease. In: Shaw V, editor. Clinical Paediatric Dietetics. 4: John Wiley & Sons Ltd.; 2015. p. 242-81.
