Abn lev drug/meds/biol subst in cerebrospinal fluid

This code signifies the presence of an abnormal concentration of therapeutic drugs, medications, or biological agents within the cerebrospinal fluid (CSF). This abnormality is not due to illicit drug use or poisoning, but rather an unexpected level of prescribed or administered substances. It indicates a deviation from the expected therapeutic range or an unanticipated presence of a substance in the CSF.

Use this code when laboratory analysis of CSF reveals an atypical level of a pharmaceutical or biological substance. This often occurs during monitoring of intrathecal drug delivery, assessment of drug penetration into the central nervous system, or investigation of neurological symptoms potentially related to medication levels. Documentation should clearly state the specific drug or substance and the abnormal level detected in the CSF.

• Do not use for abnormal levels of illicit drugs or substances due to poisoning; refer to codes in Chapter 19 (Injury, poisoning and certain other consequences of external causes).
• Always sequence this code after the primary diagnosis indicating the reason for the CSF analysis or the patient's underlying condition.
• Ensure the medical record specifies the "other" drug, medicament, or biological substance found at an abnormal level.