The amount of a 3-ketodihydrosphingosine reductase (human) when measured in cerebrospinal fluid. The trait is level of 3-ketodihydrosphingosine reductase (human) in cerebrospinal fluid (OBA_2058513, an Ontology of Biological Attributes id). Also known as: cerebrospinal fluid 3-ketodihydrosphingosine reductase (human) amount.