instruction: how many patients diagnosed with dysthymic disorder have hematology lab test category?
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.short_title = "Dysthymic disorder" AND lab."CATEGORY" = "Hematology"