What are normal results for glycine in cerebrospinal fluid?

Difficult question. Glycine is an Amino Acid that is the product of normal protein metabolism. Rare cases of inborn errors of metabolism result in a defect in metabolism of certain Amino Acids including glycine. A very rare disorder is non-ketotic hyperglycinemia where the glycine in the CSF is many times normal. The range of normal varies with ingestion of protein and depending on the form of laboratory assay.