What is the critical assessment for a 12-year-old client returning to the clinic after starting sertraline?

The critical assessment for a 12-year-old client returning to the clinic after starting sertraline is the onset of suicidal ideation. This is particularly important in pediatric patients, as studies have shown that the use of SSRIs (selective serotonin reuptake inhibitors) like sertraline can increase the risk of suicidal thoughts and behaviors in children and adolescents during the initial treatment phase or when there are dosage adjustments.

Monitoring for any changes in mood, behavior, or the emergence of suicidal thoughts is crucial, especially during the first few weeks of therapy. While other factors such as decreased sleep, weight loss, or feelings of grandiosity can be important to monitor, they are not as immediately critical as ensuring the safety of the patient, which is paramount in the context of starting an antidepressant in younger populations. The primary goal is to identify any serious side effects that could pose a risk to the client's safety. Therefore, a focus on suicidal ideation is essential in guiding follow-up care and determining the need for intervention.