**5. Clinical investigation**

Early diagnosis of PID is critical for reducing morbidity or mortality and improving treatment outcomes. Review of clinical and family history and physical examination are the first steps in evaluating the need for further laboratory investigation.

The differentiation of PIDs from other medical conditions can be complicated as the symptoms of infection (e.g., sinusitis, bronchitis, pneumonia, gastroenteritis, meningitis, or sepsis) and other manifestations often present in patients with non-PID. Hence, it is important to delineate the infectious organisms, the pattern of infections, and clinical pictures for guiding the clinical judgment, prior to focusing on laboratory testing.


#### **Table 3.**

*Clinical warning signs of PIDs.*

Due to the highly variable clinical presentations and low frequency of the PIDs, the diagnosis of patients is often delayed for years. To raise clinical awareness, JMCN has promoted 10 warning signs for children and adults (**Table 3**). Patients presenting with two or more of the clinical warning signs should be prompted for further investigation for the possible underlying immunodeficiencies and referred to immunologists for proper disease management.
