Ketogenic diet as a glycine lowering therapy in nonketotic hyperglycinemia and impact on brain glycine levels

Table 4 Cerebrospinal fluid levels of metabolites at the time of diagnosis and on ketogenic diet

CSF metabolite	Glycine (µM)			Serine (µM)		Threonine (µM)		Homocysteine (µM)	5-Methyl-tetra-hydrofolate (nm)
Time obtained	Diagnosis	KD	Off KD	Diagnosis	KD	Diagnosis	KD	KD	KD
Patient 1
Values	88	23.7	40	54.3	32.9	71.7	16.8	8.9	123
Reference range	4.7–15.4	2.9–10.9	2.9–10.9	42.9–91.6	37.8–65.5	33.4–101.9	16.1–63.8	4.7–12.4	40–187
Patient 2
Values	439	67		59.1	40	75.8	27.5	N/A	N/A
Reference range	4.7–15.4	4.7–15.4		42.9–91.6	42.9–91.6	33.4–101.9	33.4–101.9	N/A	N/A

Comparison of the levels of glycine and other relevant CSF metabolites utilized for gluconeogenic purposes pre- and post-implementation of the ketogenic diet
Age-appropriate reference range are provided for glycine, serine and threonine, which reflects the decrease observed in the first months of life. The neonatal values were developed from in 35 neonates in the first month of life [45]. Glycine, serine, threonine and homocysteine levels are in µmol/L and 5-methyltetrahydrofolate level in nmol/L
KD, ketogenic diet; N/A, not available

ISSN: 1750-1172