Discontinuation of test NC09, 4-Hydroxybutyric acid (CSF)

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a disorder affecting GABA metabolism. This disorder is generally diagnosed by the finding of elevated levels of gamma hydroxybutyric acid (GHB) in urine using standard organic acid analysis.
When MNG established CSF GHB testing (NC09), the urine organic acid procedures used in many laboratories were not specific enough to detect the GHB due to co-elution with urea. The improvement in organic acid methodology for the urine specimen type, and the fact that we have only ever detected one case of SSADH deficiency by CSF testing (and that was to confirm a case already suspected from urine organic acid screening) demonstrates that urine procedures now currently being used likely detect all cases of this disorder.
MNG will discontinue NC09 for CSF specimens; testing will not be performed on samples received after June 30, 2019.