What initial investigations should I perform for a patient presenting with neutropenia?

For a patient presenting with neutropenia, the initial investigations should include a full blood count to confirm neutropenia and assess other cell lines, kidney and liver function tests (including albumin), C-reactive protein, lactate, and blood cultures to identify any infection. Additional peripheral blood cultures should be taken if the patient has a central venous access device and it is clinically feasible. Urinalysis is recommended in children under 5 years. A chest X-ray should not be performed routinely unless clinically indicated. These investigations help assess the severity, identify possible infection sources, and guide management decisions.