Low quetiapine test concentration indicates low serum drug concentration, which may be due to the drug not being taken in the standard dosage, or the patient’s individual drug metabolism is fast, or the patient did not take the medication on time and according to the dosage. Quetiapine is a drug used in the treatment of schizophrenia. During the clinical treatment of schizophrenia patients through the daily blood concentration test can know whether the drug concentration is above the effective concentration, so as to achieve the therapeutic effect. If the concentration of quetiapine is low during the treatment period, it is necessary to clarify whether the patient has taken the medication on time and in accordance with the dosage. If the medication has been taken regularly, the dose of the drug needs to be increased appropriately in order to increase the serum quetiapine concentration. Due to the existence of individual differences, there are some fluctuations in blood quetiapine concentration in different patients taking the same dose. For example, the effective dose at the therapeutic level is lower in older patients than in the average younger patient, while the possibility exists that younger people may also have low concentrations after taking the same dose. The detection of a low concentration of quetiapine test needs to be evaluated by a doctor and treated with an adjustment of the medication, as prescribed by the doctor.