instruction: how many patients diagnosed under icd9 code 76525 had cerebrospinal fluid as lab test fluid?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE diagnoses.icd9_code = "76525" AND lab.fluid = "Cerebrospinal Fluid (CSF)"