Abn lev substances chiefly nonmedicinal as to source in CSF

This code signifies the presence of an abnormal concentration of non-medicinal substances within the cerebrospinal fluid (CSF). These substances are typically exogenous, not naturally occurring in the body, and are not related to prescribed or illicit drug use. It indicates a deviation from normal CSF composition due to external factors.

Use this code when laboratory analysis of CSF reveals elevated or otherwise abnormal levels of substances that are not drugs and are not endogenous metabolites. This often occurs in cases of environmental exposure, accidental ingestion of toxins, or contamination. Documentation must clearly specify the abnormal non-medicinal substance found in the CSF.

• Ensure documentation specifies the substance is "non-medicinal" and not a drug (e.g., recreational drugs, prescribed medications).
• Do not use this code for abnormal levels of endogenous substances like proteins, glucose, or cells; use more specific codes for those findings.
• Sequence this code as a secondary diagnosis when the underlying cause of the abnormal substance is known and coded separately.