instruction: provide the number of patients whose diagnoses icd9 code is 58889 and lab test category is chemistry.
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 = "58889" AND lab."CATEGORY" = "Chemistry"