Background: NKH sufferers cannot break down glycine due to genetically defective glycine cleavage enzyme. Accumulation of glycine disrupts brain function, limiting children’s ability to learn and continue daily activities.
Client History: Patient A, a 9-month old boy, diagnosed with encephalopathy secondary to NKH at day 4 of life. Parents defaulted follow-up after discharge. At 8 months old, he was admitted again due to sepsis.
Assessment: His weight (BW) lies on 15th percentile of WHO weight-for-age growth chart. He has high blood glycine level (573umol/L). He is tube-fed with 50 ml extensively-hydrolysed formula, 3-hourly, achieving 81% and 93% of energy (110 – 120kcal/kg BW) and protein (1.15 – 1.60g/kg BW) requirements respectively.
Nutrition Diagnosis: Impaired nutrient utilisation related to impaired protein metabolism as evidenced by elevated blood glycine level (573umol/L) and weight below 50th percentile of growth chart.
Objective & Nutrient Prescription:
To optimise protein intake with adequate energy provision to prevent muscle breakdown.
Standard infant formula is used for its low protein content, supplemented with protein-free formula, given at 90ml, 3-hourly, to achieve 97% and 107% of minimum energy and protein requirements, respectively.
Outcome and Follow-up: Glycine level still elevated (908umol/L) despite given low protein feeding. Energy intake is increased to avoid glycine level elevation due to muscle catabolism. Attempt is made to wean patient off tube feeding by using milk bottle. Parent is advised on very low protein diet at home after discharge.
Discussion: No treatment available for NKH yet. Addition of ketogenic diet to medical therapy resulted in reduced seizures and improved quality of life in infants with NKH.
Learning Points:
• Elevation of blood glycine level may be due to muscle breakdown.
• Trial to correct blood glycine level by titrating protein intake is important to establish a unique critical limit for individual patient.
• Nutrition intervention should correct not only biochemical values but patient’s nutrition status.
Disclosure Statement: HUSM and Hospital Kuala Lumpur.
