Table 1.

Summary of assay properties of the D- and L-2HG in human glioma CSF

Assay parameter	D-2HG added	Endogenous D-2HG species in CSF	L-2HG added	Endogenous L-2HG species in CSF
Analytical reference range (μmol/L)	0.05–1,000	0.05–1,000	0.05–1,000	0.05–1,000
LLOQ (μmol/L)	0.1	0.1	0.1	0.1
Inter-assay precision (%CV)	3.7	13.8	4.4	17.9
Intra-assay precision (%CV)	0.8	4.2	0.7	2.4
CSF spike recovery (%)	95.6–107.0		93.2–109.0
Freeze-thaw stability	6X thaw cycles	6X thaw cycles	6X thaw cycles	6X thaw cycles
Stability at RT for 24 hours	Stable	Stable	Stable	Stable
Interference with L-2HG	None (up to 50 μmol/L)

NOTE: Lowest limit of quantification (LLOQ) is the lowest back-interpolated standard that provides signal 2X over background with percent coefficient of variance <20%. For other measures, mean or range %CV is shown. Spike recovery ranges are reported only for the exogenous D- or L-2HG added. Freeze-thaw stability refers to the number of freeze-thaw cycles that allow <10% change in the signal from the original controls. Stability at room temperature (RT) for 24 hours of a sample was confirmed as “stable” if it met the acceptance criteria of <10% change from the original controls. Samples were run in duplicates.