These include blood tests measuring TSH to exclude hypo- or hyperthyroidism, basic electrolytes and serum calcium to rule out a metabolic disturbance, full blood count including ESR to rule out a systemic infection or chronic disease, and serology to exclude syphilis or HIV infection; two commonly ordered investigations are EEG to exclude epilepsy, and a CT scan of the head to exclude brain lesions. It is important to rule out a delirium which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness and indicates an underlying medical illness. There are several psychiatric illnesses which may present with psychotic symptoms other than schizophrenia. These include bipolar disorder, borderline personality disorder, drug intoxication, brief drug-induced psychosis, and schizophreniform disorder.
Investigations are not generally repeated for relapse unless there is a specific medical indication. These may include serum blood sugar level (BSL) if olanzapine has been prescribed previously, liver function tests if chlorpromazine, or creatine phosphokinase (CPK) to exclude neuroleptic malignant syndrome. Assessment and treatment are usually done on an outpatient basis; admission to an inpatient facility is considered if there is a risk to self or others.
The most widely used criteria for diagnosing schizophrenia are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, the current version being DSM-IV-TR, and the World Health Organization's International Statistical Classification of Diseases and Related Health Problems, currently the ICD-10. The latter criteria are typically used in European countries while the DSM criteria are used in the USA or the rest of the world, as well as prevailing in research studies. The ICD-10 criteria put more emphasis on Schneiderian first rank symptoms although, in practice, agreement between the two systems is high. The WHO has developed the tool SCAN (Schedules for Clinical Assessment in Neuropsychiatry) which can be used for diagnosing a number of psychiatric conditions, including schizophrenia.[ DSM IV-TR CriteriaTo be diagnosed with schizophrenia, a person must display:
· Characteristic symptoms: Two or more of the following, each present for a significant portion of time during a one-month period (or less, if successfully treated)
o disorganized speech (e.g., frequent derailment or incoherence; speaking in abstracts). See thought disorder.
o grossly disorganized behavior (e.g. dressing inappropriately, crying frequently) or catatonic
o negative symptoms, i.e., affective flattening (lack or decline in emotional response), alogia (lack or decline in speech), or avolition (lack or decline in motivation). Note: Only one of these symptoms is required if delusions are bizarre or hallucinations consist of hearing one voice participating in a running commentary of the patient's actions or of hearing two or more voices conversing with each other.